# line driver vs usb dac



## timmgrimm (Feb 4, 2013)

I'm deployed right now and I'm doing the research for a tablet car pc build when I get home. I'm planning on using a rooted nexus 7 as the tablet. It supports the use of a USB dac or I could use the 3.5 > rca > line driver. Which provides better sq? I'm trying to keep the price fairly low. I'm looking to keep the whole build to about what I'd pay for a decent double din DVD player from amazon $350-$450. Thanks


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## chad (Jun 30, 2005)

You thinking a DAC that is simply powered off the USB? What do you have in mind on that end?


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## Ultimateherts (Nov 13, 2006)

First off thank you for all your service and second it depends. For some a USB dac is not loud enough and for others it is. I'd say try the DAC first then add a line driver if needed. Either way if your going analog then a dac will always make it sound nicer. A line driver will just add more volume.


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## timmgrimm (Feb 4, 2013)

chad said:


> You thinking a DAC that is simply powered off the USB? What do you have in mind on that end?


Yes. Just get an otg y splitter, hub on one side, power cable through other. Im hoping i could power the dac and a hdd. Idk which DAC though. I'm looking but nothing is jumping out. Never messed with one, so i don't know the period and cons of each. I'd love some suggestions. What would be good for 1 set of components, 1x coax and one sub? And as i said earlier, I'm looking to keep the total build cost religiously low. And that's including base model nexus. (I plan on using a HDD for the actual storage)

As far as sq, I was figuring that's how it went. 
And lastly I appreciate your support.


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## timmgrimm (Feb 4, 2013)

Also, for power, idk if its possible but maybe I could use 2 power cables. 1 plugged in otg and 1 in hub. Don't know if it would increase power output.


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## Ultimateherts (Nov 13, 2006)

I believe the specification for USB is:

The USB 1.x and 2.0 specifications provide a 5 V supply on a single wire from which connected USB devices may draw power. The specification provides for no more than 5.25 V and no less than 4.75 V (5 V±5%) between the positive and negative bus power lines. For USB 3.0, the voltage supplied by low-powered hub ports is 4.45–5.25 V.

A unit load is defined as 100 mA in USB 2.0, and 150 mA in USB 3.0. A device may draw a maximum of 5 unit loads (500 mA) from a port in USB 2.0; 6 (900 mA) in USB 3.0.

As quoted from:

Universal Serial Bus - Wikipedia, the free encyclopedia


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## timmgrimm (Feb 4, 2013)

So there is a maximum amount of power it will provide, but if two power supplies were connected would they both provide power through the system, I.e tablet, hdd, and dac. There is a maximum amount of power that can run one way on the bus but I'm wondering about if its possible for providing power using this method: a tablet connected to a otg y cable/ usb power cable connected to one side/ a hub connected through the other/ connected into the hub would be the USB powered DAC/ a usb powered hdd/ and another usb power cable. Depending on if this can work, my biggest fear is that there would be too much power draw for a single cable.


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## timmgrimm (Feb 4, 2013)

So I'm continuing to research DAC but I'm not getting it. It seems that the DACs output into a single RC cable hoe do I then turn that into 2x components 2x coax and 1x subwoofer? I really need someone to help me understand. Will this setup require an amp for the mids and hi's? Would it be best to use a 5 ch amp? Would that said amp take that single RC and turn it into multiple signals? I need help


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## charliekwin (Apr 22, 2012)

The DACs you're looking at are just converting the full-range digital audio to analog. Depending on how you're planning on building your system, you'll want a DSP and/or crossovers to get those outputs.


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## timmgrimm (Feb 4, 2013)

Thank you. I am literally sitting here asking myself " what am I not getting?"

Which is better route?


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## .:stealth:. (Oct 29, 2011)

I went with the Audison Bit ten D for my setup. Has a toslink input and five 4volt RCA outputs, 2x fronts 2x rears 1x sub. Basically I have my sound card's optical output feeding the bit ten D, simple as that..


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## timmgrimm (Feb 4, 2013)

I've nothing but good things about that unit so far. As much as I'd love to, i don't have it in me to put that much into one piece. (Too many plans for when i get home.) I'm looking at the audiocontrol Lc7 with aux input feeding a five channel amp. Needs to be one amp because its going in a 2003 tundra and the sub will be under the rear seat. I've been looking at the mini DSP. Would that do what I need it to. I need to do some more reading on that thread to find out the just of it. If not, maybe an add on later to do some processing.


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## timmgrimm (Feb 4, 2013)

Just an update. So I'm thinking that based on build cost I'm going to start out with using 3.5 to rca, clarion eqs746, to five channel amp. Buying a while system gets expensive quick.


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## matty2013 (Jul 10, 2012)

I have a similar question. 
I'm looking to put a nexus 7 in my car, I am also using an Alpine pxe-h660, and have been wondering whether I should use the 3.5mm Aux output to RCA, into DAC then into the PXE-H660, then to my 4 channel amp. 
Or should I just do 3.5mm Aux straight into the H660?
And would a line driver even be necessary, or will the H660 boost the signal that it outputs to the amp?


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## timmgrimm (Feb 4, 2013)

So I decided to go with a behringer uca222 to a cadence ceq-773 eq. I'd be willing to bet that you wouldn't need a line driver with that PXE-H660. 

Here is a great thread for a tablet build. 

I made all of my equipment purchases and am gonna start my build when I redeploy home in a few weeks.


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## RayBob (Sep 10, 2012)

I'm not a seasoned audiophile, but I looked over that Behringer UCA222 DAC's specs, and it's not really much better than using the onboard headphone out to feed your Cadence CEQ-773... which has much cleaner specs.

I compared it to a decent entry level USB DAC with the ESS Sabre ES2093 DAC chip, like this Hifimediy Sabre USB DAC ES9023 and really think you would notice a difference.

Maybe someone with more experience can chime in?

By the way I have one of the above Hifimediy DAC's on my home PC, and it sounds very good. I also have the ODAC, which is also ESS Sabre ES2093 based, in my car pc feeding an MS-8, and it also sounds very good.

-Robert


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## Ultimateherts (Nov 13, 2006)

I just think DACs are so lackluster when it comes to the number of outputs you get vs a pro audio soundcard in the same price range!!!


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## matty2013 (Jul 10, 2012)

Ultimateherts said:


> I just think DACs are so lackluster when it comes to the number of outputs you get vs a pro audio soundcard in the same price range!!!


Would you advise skipping out on a DAC if I output from the nexus 7 straight to the PXE-H660? (This will be my first experience with sound processing, and I liked the idea of the mic auto tuning to ease into it, and learn about working my way up to pro-ish audio)


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## RayBob (Sep 10, 2012)

Since the PXE-H660 will give you all the outputs you need, I would try it first and see how you like it. You can always add the DAC later to get cleaner sound.

A DAC does only have stereo output so you do need a processor or at minimum an clean EQ to give you all the outputs you need.


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## Ultimateherts (Nov 13, 2006)

matty2013 said:


> Would you advise skipping out on a DAC if I output from the nexus 7 straight to the PXE-H660? (This will be my first experience with sound processing, and I liked the idea of the mic auto tuning to ease into it, and learn about working my way up to pro-ish audio)


I was from the standpoint of using a carpc not the Nexus. Although it really doesn't matter what you use as long as you have enough outputs. The whole idea of a carpc is to eliminate the traditional car audio extras as much as possible. Examples being why buy a car audio processor when the carpc can do more than that.


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