# Need clarification on input signal - speaker-level vs line-level



## bigd480 (Oct 14, 2008)

I installed a JVC Arsenal KDA735BT HU into a 97 Maxima w/ the stock Bose system (amp at each speaker, 1ohm speakers). There are 2 Metra integration harnesses that can be used, the 70-7550 (uses speaker-level outputs) and the 70-7551 (uses pre-amp outputs).

I opted for the latter, thinking RCAs would provide the cleanest signal possible, since I'm using these 15yr old speakers/amps. Due to the Bose system not using a common ground, I also had to use a 4-channel ground loop isolator to avoid pops when turning deck on/off (still don't understand why this works, but it did).

When discussing with another Maxima forum member, they felt my approach was counter-productive:



> "Amplified IS 'high', non amplified IS 'low'. BOTH are simply voltage. So a 'high voltage deck' would be no different.
> 
> You wanted the 'cleanest signal possible' yet you added more to the chain to be counterproductive. You went backwards, not forwards my friend."


I'm a bit of a car stereo noob, but that just still sounds wrong to me. If it was so similar why would people use LOCs / why would amps have high and low inputs / why would people pay more for decks with higher voltage preouts?

I'm not interested in getting into an internet argument but am still curious if he is correct and if not, why. I have a feeling that voltage isn't just voltage and the speaker-level outputs are still "noisier".

I would like get some opinions from the experts here - any thoughts?


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