# Average Joe Review: Stereo Integrity SIQ Series Amplifiers



## LaserSVT (Feb 1, 2009)

Hello ladies and gentleman! I realize its been a while since I have done an Average Joe Review. I have always called it that because I write my reviews in a way that's more for the final user, the average guy that does not have thousands in test equipment to get all the hard numbers and just has to rely on what you hear vs what the numbers say an amp should do. This is why I normally just do speaker reviews and not electronics reviews as most hard core enthusiasts only care about the numbers more then they care about how the component actually performs in the real world. They do care about real world performance but thats only if the amplifiers live up to the numbers their manufacturer claims. That is important but I have found over the years numbers don't tell the full story. In my experience all amplifiers do not sound the same and amplifiers with near identical specs can sound vastly different from one another. Basically this is an objective review. Some do not like that, some do. I have tested and spent many hours listening to amplifiers from all brands including Mosconi, Brax, Sinfoni, JL Audio, Focal, JBL, Arc, Zapco, Helix and countless others and over the years have accumulated a lot of knowledge in regards to tonality and if an amplifier "colors" the music at all and if their "sound signature" changes at different volume levels.
I use music that I have heard thousands of times before on real reference home systems and car systems. Music where I know the hidden details are and how a note or instrument should sound. This time I am pitting them against some amplifiers that are well established as excellent SQ amplifiers that are rated at the same power and did a semi A/B test against these amplifiers meaning I did 100s of hours of listening to one brand and then 100s more with the same songs on the Stereo Integrity amplifiers driving the same speakers in the same environment and using the same source units. I also used the same tune for both because all amps SHOULD sound the same. Or I guess I should say they shouldn't "sound" at all but simply amplify the signal being sent without adding or taking away anything at any volume level.
I also want to point out that I never get equipment for free or even at a discount. I pay for what I test and in some cases I am allowed to borrow a component to test but have to return it when I am done. That way I make sure I stay unbiased because no matter how hard you try, that free part may get a subconscious favoring without you even knowing it.

I also want to thank Nick Lemons of Stereo Integrity for trusting me with his amplifiers to test and review. I also want to thank Matt, Everett and the crew at Crow Concepts here in Waco Texas for the amazing job they did doing this installation and making it look so good. Very impressed with their work and customer service.

Now that we have that out of the way lets get to why we are here. Today I am reviewing a few of the new offerings from Stereo Integrity now that they have decided to get into the amplifier world. Specifically I am reviewing the SIQ 125.4 (16.5″ x 8″ x 2″ ), the SIQ 75.4 (14″ x 8″ x 2″ )and the SIQ 1500D (16.5″ x 8″ x 2″ ). There are several more amps they make such as the 200.2 (200wx2), the 200.4 (200x4) and the soon to be released 3000D (3000x1). As of this time you can go to Stereo Integritys website and see the pricing and specifications on all of the class A/B amplifiers but you will not see the class D mono subwoofer amps yet as I am kind of letting the cat out of the bag on them.










For this review the source and processing units are from Alpine. The Alpine X009-GM deck hooked to the Alpine PXE-0850S with a borrowed FiiO M11 playing the music via the AUX input so I can have as clean as a signal as I can get with FLAC since I no longer have all the CDs I once had and didn't want MP3 to degrade the signal at all.
The drivers I am using are, to me, my reference speakers of choice. For the highs I am using Infinity EMIT-N titanium ribbon tweeters on axis because they have the ability to be completely transparent and the ribbon reproduces upper frequencies to perfection. For midrange I am using Audio Development MM series 4" midrange on axis. These are some of the cleanest and accurate mids I have ever heard equal to any other high dollar midrange made. The 60-400hz area is being covered by Audio Development Vipera F6 6.5" driver a bit off axis. These mid-bass drivers have a clairity and punch to them unlike any other 6.5 I ever heard. They play to well below 50hz without any issue or colorization. Finally for subwoofer duties I am using the Audiofrog GB12 12" subwoofers in an optimum sized sealed enclosure that was custom made with bracing and heavily coated to seal properly and not resonate with the vehicle. The vehicle itself is a 2009 GMC Denali Sierra that has several hundred pounds of SDS Showdown MLV, CCF and CLD tiles covering the entire interior from the floor to walls to doors and anywhere it could cover any metal parts. Dashboard is carpeted to help with any reflections. Music was all listened to with eyes closed so visually I wasn't distracted.

The amplifiers I am doing the back to back comparison with are the Helix G Four (little more power than the SIQs) on the tweeters and midranges. A Helix G ONE (little less power than the SIQ) on the subwoofers and lastly a Helix G TWO on the mid-bass drivers that's rated at identical power per channel as the SIQ 125.4 so it should sound the exact same. The Helix G series does have a much higher S/N ratio (106db vs 91db) with a THD that's within a thousandths of each other.

The amps arrive in a very nice wooden box that contains spare fuses and all the needed mounting hardware.



















The amplifiers first had a thorough inspection using my own quality control team. They seemed to like them.











The first amplifier up is the SIQ 75.4 that is driving the Infinity EMIT-N tweeters and the AD MM4 midranges. These amplifiers are rated at 75 watts per channel and are 4 channel.
This particular one is a pre production unit and the only real change will be bespoke SI power capacitors in them but will have pretty much the same ratings just with a slightly higher thermal rating. They have no onboard processing of any kind. No crossovers or bass boost, just a gain knob for each channel. This is the same for all their A/B amplifiers. Only independent channel gain control and nothing else. The manufacturer wanted the signal traveling through them to be as pure as he could get them and did not wish to have anything that MAY color the sound added to them. The only exception is on the sub amplifiers which will have a remote gain knob. This is not a "bass knob", just a way to quickly adjust bass level if you are like me and listen to every kind of music.
Just going off aesthetics they are a very pretty amplifier. A solid brick of a heatsink with a clear cover so you can see the componentry inside. The capacitors have a mellow LED behind them giving the amplifiers a unique look at night when powered on. Note that the center amp is a very pre production amp and has not had the LEDs added as of yet.










The amplifier takes in 4awg power wire perfectly and you can run 12 awg speaker wire without issue. They have Tiffany style RCA connections as well which I find is a nice touch.










































Next in line is the 125 watt by 4 amplifier. Its only a hair larger than the 75.4 but is a very heavy brick. This one is a production unit and you can see the SI spec capacitors in it that all the amps will get when in full production. Just like its little brother it only has gains for each channel and nothing else. It as a few more FETs (for obvious reasons) but has the same Tiffany connectors and some larger on board fuses.


----------



## LaserSVT (Feb 1, 2009)

Continued due to picture limitations.....
The 3rd amplifier in this review is the mono block 1500D amplifier. Its rated for 1500 watts into 1 ohm, 1000 into 2 ohm and 500 into 4ohm. Again, this is a pre production amplifier so it does not yet have the slightly higher temperature rated capacitors, does not have the SI logo on top nor does it have the LEDs behind the caps for that warm glow at night time. While you can see multiple potentiometers (should be gone on production version) on it the only one thats being used is the gain. There is no bass boost or adjustable subsonic filter (factory subsonic filter is 5hz) or a low pass crossover. The amp (at the time of this writing) will have a frequency range of 5hz to 350hz.
This is quite a heavy amp and the construction look spectacular, more so considering its not a full production one yet. It has dual 4 awg power inputs as well and needs them due to the sheer output capability it has.













































Now I wanted to do this review as if they were a permanent part of the stereo. I don't test them on a bench with a nice controlled power supply with banks of batteries. I want a real world sound test of them. See how they heat up, how/if vibration hurts them and let them be powered by a standard vehicles power system using a factory alternator and a normal old lead acid battery. That way I can see if power degrades with the vehicle pulling the power it needs to run everything and if a "smart" alternator that will vary voltage from 11 volts to 15 volts effects them. So we wired and mounted them in a way that would mimic a normal installation in a vehicle.



















Now on to the review on what I have found with these amplifiers after nearly 100 hours of critical listening with the truck both on and off and many hours of listening while driving since that's what car audio amps are for. Enjoying your music while you travel to your destination.
First thing I noticed was their start up sequence. No loud fans turning on, no thud, no dancing lights or any of that. They remind me of a nice mid to high end home amplifier where at first you hear 3 solid "clicks" as they power up followed by several quieter "clicks" after the amps do their pre check fireup and are now ready to play. Its a small thing but adds a nice subtle touch to the experience as you feel you are about to be treated to something good sounding.

So I loaded up my music mix into the FiiO with the same playlist of songs I have hears 1000s of times on countless systems and just spent a few weeks taking notes as I listened to them on the Helix amplifiers.

Started with an old goodie of "Dreams I'll Never See" by Molly Hatchet. I like this song to hear detail of tambourines during the guitar solo. I also love to hear the detail of the leed singers voice after the solo at volume as it can sometimes sound harsh when he sings "All right, yeah yeah". The 75.4 reproduced them to absolute perfection. I honestly couldn't hear any difference between it and the Helix amp until I cranked it to near limits. The Helix would pull the tambourine back a tad and his voice is much more gruff in the "All right, Yeah yeah" section where as on the SI amp the tambourine stayed crisp and clear and his voice stayed smooth for that bit. Yes for the rest of the song he sounds a bit gruff but that's just Molley Hatchet songs. He growls a bit when he sings.
Next I went to Phil Collins "In The Air Tonight". I use this song pretty much for the electric drum solo he does near the end that any music lover knows well. I always thought that there was an odd distortion in that drum solo start off right after he sings "Its no stranger to you and me" and been told thats normal but its a sound I never heard on some very high end sound systems nor had heard in very high end competition cars. The Helix amps didnt seem to make that distorted sound within that drum solo as well unless I was at level 21 or higher on the deck (deck peaks at level 35 with level 33 being the end of its clearest signal) but with the SI amp it stayed perfectly clean and defined. No colorization at all.
Next song was Fleetwood Macs "You Make Loving Fun". This song has a lot going on in the details. Christie Mcvee has such a smooth and powerful vocal ability and her voice remained prominent and clear where as in some systems I hear her get overpowered by the instruments. Was not the case here. At 2:22 into the song when there is the little background sound by that instrument that clicks when you spin it, sorry as I have forgotten what its called, comes across clear as day from the far right of the stage. Mick Fleetwoods drumming is always excellent and the attack and decay was as good as I have ever heard in my life. The drums sound real and not reproduced like a lessor amp would do. His cymbals sound spot on and solidly planted to the right of center stage just like they should be. The kick drum has solid impact with no muddyness. The rhythm guitar is so nice and detailed hanging just to the left of center stage with the leed guitar staying perfectly to the center right until latter in the song where he moves to the center and then back over to the left again.
I then switched to something a little more current. "Folk Hop Sound" by Judah and the Lion. I like this song to test stereo separation and height as at the beginning the guitar moves from left to right repeatedly and then rises in height when it goes center stage. The amplifier did it so well that it was more of "dual mono" sound than a stereo amp. Full and complete separation there. Then the digitized kick drum comes in and is a very low frequency that should have a very rapid attack and decay with a solid thud felt in your chest. I have played this track many times and have often been disappointed in the bass with many systems. You get the thump and the deep bass line but its almost a solid kind of bass line. In this test the bass line stopped perfectly and each thump was distinctive and detailed with a very solid thump to your chest. Then the mandolin comes in and made my arm hair stand up. So crisp and clean. Yet again it sounded like the instrument was in the car and not just hearing a recording of it.

Next up is Pink Floyds live version of "Learning to Fly" (2020 remastered version). This song put a smile on my face as I felt like I was there. The drum solo start off was spectacular. With the bongos solidly planted on the right and the wood clackers on the left with the kick drum/main drums center stage and you can hear it BEHIND the singers and guitarists. Then the bass guitar comes in. It was a nice solid "bum bum bum bum bum" of each note that didnt blend into each other. When the leed singer and background singers come in the clarity was spot on. No sibilant s's and very breathy backup singers. Going into the musical middle part of the song was a pure treat and as the bass rolled in before he starts singing again was deep and thunderous. As he sings the high hats are sharp and crisp with no fatiguing of your ears as at this point I was moving near max volume by the 7th time I played the song. I was no longer listening to a stereo, I was just enjoying the music. Just purely lost in the sound...... this is what I want out of a stereo where it sounds so right that you no longer are judging the stereo but simply enjoying the music you are listening to.

Next up was to see what the sub amp was really made of. I use "Bass I Love You" a lot due to the super deep subsonic frequencies produced. This songs has a lowest note centered at 7hz and truth be told I have been missing the impact of that not for quite a while. I havent heard and felt it clearly since my Mosconi Zero amps and old JL 1000/1 amp I had before. Everything since then (Arc, Zapco, Helix, JL HD) just did not want to go that deep. I knew the subs could do it. I have seen and heard them do it before. With the 1500D they now stroke the hell out of that note and the bass is THUNDEROUS! Mirrors become unusable, radar detector bounces a solid inch and you can feel it in your throat.

I am going to end this review on the last song that surprised the heck out of me. "State of Play" by Yes. This song starts off with a powerful electric guitar rift and some hard smacks of the drums followed by a deep driving bass line of the bass guitar and kick drum combined that attack you right away. The song then slows down a tad and there is a little short guitar strokes in the background to add to the song that have that classic 60s sound guitar tone. Right after that is when the song comes in and throws all the instruments at you with a bass line that is super deep and thunderous. I listened to the song several times at normal volume and the definition and placement was the best I have heard to date on any system I have ever had in any one of my vehicles. At the 3:30 mark a bass guitar and synthesizer come in playing a processive series of deeper and stronger bass notes until well past the 4 minute mark that were easily the deepest and strongest I have EVER heard them in an SQ based setup. They were so strong that for the first time in my life I had an SQ system set off my other cars alarm with the bass. Windows up, tuck fully sealed and sound dampened, nothing resonating or vibrating. Just so deep and strong that it set off the vibration sensors. Granted I was at the end of my testing so I had the system at max output but it sounded so clean, so clear and so detailed I just wanted to enjoy the song and not critique it. I have never heard that song sound so clean and powerful before and I played it when it first came out on Infinity IRS V speakers with Carver Silver Seven amplifiers driving the main towers with the original servo amp on the 12-12" woofer towers.

The subwoofer amp is quite impressive. It does make more than you pay for:









So here are my final thoughts. This is just an objective test and I am only using my decades of listening to music on multiple very high end systems all the way to ebay specials.
The Stereo Integrity SIQ series of amplifiers are seriously impressive. They look spectacular. The first words anyone says when they look at them is "Wow, those look spectacular!". Every single person that's seen them in real life instantly falls in love with their looks. But unlike a beautiful supermodel they have actual substance to them. They have a hidden beauty and that's pure, clean, un-colored amplification. These are the first amps I have tested in 5 years that made me go "Wow!" when listening to them. This is Stereo Integritys first foray into the amplifier world and they started with a bang! People have been wondering for months now if they could perform like they look and I am here to say they do sound even better than they look. From the sounds they make when they power up to the sound they reproduce when playing music is fully first class all the way.
They are a truly impressive amplifier and I do believe I will be calling Nick and telling him I want to buy them all, even the 200.4 and 200.2 just to have on the shelf so I can look at them. These outperformed the Helix G series easily despite having less power (except the sub amp) and having a much lower S/N rating. At high volume and on pause I could hear the tweeters "hiss" ever so slightly with the Helix amps and with the SI amps there is almost none. You have to be in a dead silent environment to hear it. I couldn't hear them in the truck or when outside at all. I had to put it in the garage, close the doors, make sure the lights were off (because they have built in fans on the truck) and get my ear right up to the tweeter to hear anything at all.
Musically they are spectacular. They add nothing to the signal they receive except pure power. They are well worth the money and then some.

Downside..... The 125.4 does get warm. Not excessively but I did see up to 125* on its heatsink after 2 hours of testing going from normal to high volume levels. The mono amp and 75.4 stayed cool with the sub amp hitting 92* and the 75.4 hitting 99* on a 76* day.
Also the mounting feet are a little odd and feel flimsy. I dont care for how they screw to the back of the amp and then sick out of the sides so the amps can not be stacked end to end unless you make your own mounts that attach though your amp mount from behind. Also the bass knob needs some work. I cant really call that a complaint as the mono amps are not yet done and the knob sent with it isnt fully specd to the amp so its "clip" light does not function properly. SI is aware and will have that sorted by the time the amps are available for purchase. Other than that I am struggling to find something negative to say about them.


----------



## TunezX (Aug 20, 2020)

Kewll review. Maybe someone can put it up against the “copt-cat” for an a/b review. Thanks!


----------



## LaserSVT (Feb 1, 2009)

TunezX said:


> Kewll review. Maybe someone can put it up against the “copt-cat” for an a/b review. Thanks!


Big D already reviewed the copy cat version and it was horrid. Didnt make rated, it made odd noises, sounded like garbage. He has a video on YouTube on it. He should be getting one or two of the other amps to test them but I already know that they all do a nice chunk over rated power.


----------



## bertholomey (Dec 27, 2007)

Thank you for the thorough, well written review! I skimmed this time, but will go back and read more thoroughly. They look great in your install as well!!!


Sent from my iPhone using Tapatalk Pro


----------



## mikey7182 (Jan 16, 2008)

Great review, and those are ****ing gorgeous aesthetically! Damn,  Did I miss the official release date?


----------



## kmbkk (Jun 11, 2011)

Thanks for the review on these amps! I actually pre-ordered the 125.4 and 200.2s, which were delivered today while I’m out of town😒 I look forward to installing them and getting them dialed in. This review makes me even more excited!


----------



## ckirocz28 (Nov 29, 2017)

LaserSVT said:


> Continued due to picture limitations.....
> The 3rd amplifier in this review is the mono block 1500D amplifier. Its rated for 1500 watts into 1 ohm, 1000 into 2 ohm and 500 into 4ohm. Again, this is a pre production amplifier so it does not yet have the slightly higher temperature rated capacitors, does not have the SI logo on top nor does it have the LEDs behind the caps for that warm glow at night time. While you can see multiple potentiometers (should be gone on production version) on it the only one thats being used is the gain. There is no bass boost or adjustable subsonic filter (factory subsonic filter is 5hz) or a low pass crossover. The amp (at the time of this writing) will have a frequency range of 5hz to 350hz.
> This is quite a heavy amp and the construction look spectacular, more so considering its not a full production one yet. It has dual 4 awg power inputs as well and needs them due to the sheer output capability it has.
> 
> ...


Damn you! I was looking at these and the Mmats HiFi amps for an upgrade from 2 JL Audio XD 400/4's. Now, thanks to you, I guess I have preorder these and wait!


----------



## Ssopus (Dec 22, 2020)

Well written review on some serious eye candy. Thanks fir the post.


----------



## Isaradia (Apr 14, 2020)

I'm jealous


----------



## Granite (Jun 3, 2020)

Thanks for taking time to post this - very informative. Was there anything you didn’t like - or thought could use improvement - for any of the amps in this review?


----------



## LaserSVT (Feb 1, 2009)

Granite said:


> Thanks for taking time to post this - very informative. Was there anything you didn’t like - or thought could use improvement - for any of the amps in this review?


Just the style of mounting but thats kinda nit picking. Also wish there wasnt any subsonic filter but I can live with 5hz. lol


----------



## miniSQ (Aug 4, 2009)

I would need to know whats under those copper covers? i don't think Nick would mind if you popped one off.


----------



## LaserSVT (Feb 1, 2009)

Ask him. If he says yes then maybe I can make it happen. They are just coils though. They ae not fakes like the clones. 
Also here is a shot including the 200.2 and the 200.4!


----------



## OSB (Feb 12, 2021)

LaserSVT said:


> Ask him. If he says yes then maybe I can make it happen. They are just coils though. They ae not fakes like the clones.
> Also here is a shot including the 200.2 and the 200.4!


What are the dimesions on the SIQ 1500? Great review by the way. Much appreciated.


----------



## miniSQ (Aug 4, 2009)

LaserSVT said:


> Ask him.


I bet he is watching this thread


----------



## LaserSVT (Feb 1, 2009)

miniSQ said:


> I bet he is watching this thread


Probably not. Hes on vacation this week.


----------



## LaserSVT (Feb 1, 2009)

OSB said:


> What are the dimensions on the SIQ 1500?
> 
> What are the dimesions on the SIQ 1500? Great review by the way. Much appreciated.


16.5″ x 8″ x 2″ 

Sorry, I did neglect to put their sizes up.


----------



## miniSQ (Aug 4, 2009)

LaserSVT said:


> Probably not. Hes on vacation this week.


i envy him if he can steo away from his phone for a week


----------



## cman (Aug 24, 2020)

I noticed Onn brand semiconductor for all the T04 transistors in the A/B model and Onn brand mosfets in the class D - Ive seen other high end ampliifers like the ones from D'Amore engineering using parts from Onn - So I'm asuming they are a good manufactuer.

I also saw Rubycon capacitors so thats two big wins in my book just from first glance.


----------



## LaserSVT (Feb 1, 2009)

cman said:


> I noticed Onn brand semiconductor for all the T04 transistors in the A/B model and Onn brand mosfets in the class D - Ive seen other high end ampliifers like the ones from D'Amore engineering using parts from Onn - So I'm asuming they are a good manufactuer.
> 
> I also saw Rubycon capacitors so thats two big wins in my book just from first glance.


Yes sir. When SI specd the amp design they wanted tight tolerances and for them to be as clean as possible so they spent the money on better components. They are using what $2000 amps use at 1/3 the cost which was a big plus to me as well. That much power and clarity from an amp under $700 is impressive to me.


----------



## ckirocz28 (Nov 29, 2017)

Anyone know what the 3000 watt amp dyno's at?


----------



## kmbkk (Jun 11, 2011)

ckirocz28 said:


> Anyone know what the 3000 watt amp dyno's at?


Haven't seen any dyno #’s yet, not sure if Nick has it to dyno yet anyway. If I had to guess, based on how the current ones are, I’d say it will do a little over rated pretty easily.


----------



## OSB (Feb 12, 2021)

ckirocz28 said:


> Anyone know what the 3000 watt amp dyno's at?












This was what SI posted in their Facebook comments section for the SIQ 3000.1 and 1500.1.


----------



## ckirocz28 (Nov 29, 2017)

OSB said:


> View attachment 294626
> 
> 
> This was what SI posted in their Facebook comments section for the SIQ 3000.1 and 1500.1.


I just came back here to post the pic for the 3000 watt dyno, but thanks for digging it up!


----------



## ryyo (Jun 29, 2009)

Is anyone else on here using these amps? I've been considering the 125.4 to replace my aged JL 300/4, especially since the SI amps are on sale right now. Looking for more impressions.


----------



## Stycker (Jan 31, 2018)

I am using the 125.4 and love it. I used the JL 300/4 many years ago and remember it to be underwelming. That was at least 12 years ago so not a fair comparison. The SI amps are legit sound quality. I'm also using 200.2 and 1500.1. They are all clean and powerful. I was price shopping between these and Zapco AP and Arc Audio SE. The SI amps are over half the cost but not half the amp as the others. Price was not the only factor. The SI amps look better and are smaller. I probably could have got the 75.4 instead of the 125.4 as it is being used for mids and tweets.


----------



## dmparker5725 (Feb 20, 2014)

I am using the 125.4 as well for midbass and tweeters. Fantastic amp! It is quiet, clean and from what I can tell, adds nothing to the sound. I have more tweaking to do with my DSP but I am enjoying what I am hearing so far. Mine replaced a very good Alpine X-Series amp. This one is staying.


----------



## bertholomey (Dec 27, 2007)

I had the opportunity to get a good long demo in this vehicle, and I was very impressed with the performance of the amps. Of course, not the same impact as someone who recently tested between two amps or swapped out an amp and installed these in their place. But....they were powerful, silent, and beautiful - great in my book. 






































Sent from my iPhone using Tapatalk Pro


----------



## EmptyKim (Jun 17, 2010)

bertholomey said:


> I had the opportunity to get a good long demo in this vehicle, and I was very impressed with the performance of the amps. Of course, not the same impact as someone who recently tested between two amps or swapped out an amp and installed these in their place. But....they were powerful, silent, and beautiful - great in my book.
> 
> 
> 
> ...


Bruh, you missed the real question. How was the 24?!?


----------



## bertholomey (Dec 27, 2007)

EmptyKim said:


> Bruh, you missed the real question. How was the 24?!?


Extraordinary! Tuned for SQ - it was fast, it was subtle when it needed to be, it hammered when called on to do it - electronic music and heavy rock. With the tune that was on it, very balanced sound - you knew it was doing its thing without making a nuisance of itself. Absolutely brilliant!


Sent from my iPhone using Tapatalk Pro


----------



## ryyo (Jun 29, 2009)

So I received and installed the SIQ 125.4 today, and so far so good. With very little adjustments, it has made my midbasses and midranges sound very nice. The 300/4 wasn't bad by any means, but the 125.4 seems better IMO so far (possibly attributed to just having more power). There seems to be no discernable noise with the 125.4, whereas the 300/4 did produce some noise. And the 125.4 looks great to boot. There is, however, a slight nick (no pun intended) on the underside of the plexiglass(?) though that I didn't notice until after I installed it and removed the peel off stuff. There's no way I could have caused that. All in all I'm very happy with the purchase.


----------



## Black Rain (Feb 27, 2011)

Reviving this thread......

Great review of the SIQ amps. Curious, has anyone Dyno Tested the SIQ 125.4 and the 75.4. I have seen the YT videos of the 200.4, which do show a significant amount of Headroom? So just wandering about how much the 125 and 75 are giving. At the end of the day we want to know how much CLEAN, UNFILTERED and UNDISTORTED power we are sending to our speaker even though we know they really see full power in SQ.


----------



## Kenny_Cox (Sep 9, 2007)

I was just browsing the site and came across this review. thanks for sharing, maybe I’ll keep the ones I have for a while now… 🤣🤣


----------



## WASP (Sep 12, 2020)

Kenny_Cox said:


> I was just browsing the site and came across this review. thanks for sharing, maybe I’ll keep the ones I have for a while now… 🤣🤣


 Same, great review! I'm sold on my next build.


----------



## stonekutta (5 mo ago)

i ordered the 3000.1, the 200.4 and the 125.4 . these will be powering 2 sql-12s ported with a 3-way Si component setup and a set of cdt-mx designs 2492 6x9's. full active helix mk2 (except I may run 6x9 passive-running out of channels) with a denon dct-z. all items selected from diyma reviews like these! thanks for the detailed review!


----------



## 06S2k07Si (Nov 18, 2013)

Thanks LaserSVT for the time to write the review. It was the tipping point for me to purchase some. I received my 125.4 and 1500.1 the other day and finally got a chance to test it today! Initial impressions are excellent! More A/Bing to come in the next few days. I very well may get a few more!

Thanks brother!


----------



## 06S2k07Si (Nov 18, 2013)

Do we know who was involved in the design of these?


----------

