I notice the 9857, one of Apline's top of the line decks, only has 2V output, while other decks from Sony and JVC come with 4V/5V at a lower price point.

How important is the voltage number?

 

As I understand it, pre-amp voltage is important in that it indicates (doesn't determine) how much power gets to an amp, so you don't have to turn the gain up as much on an amp if you're pushing more volts. If you don't have an amp, it doesn't matter, but if you do have an amp, what really matters is that the amp has a good low noise ratio to begin with. I'd focus on a good HU and amp and not worry about 2v outputs.

The Alpine has a lower output, but is known for sound quality. If your amp is quality and powerful enough, sound volume isn't really an issue. What the amp sees and amplifies is - so you want to be sure you're getting clean sound from the HU to begin with.

 

I agree. What you gain with higher pre-amp voltages is that you can turn DOWN the gain on the power amp and get the same volume at the speakers. Turning the gain down just reduces the voltage the amp sees to what it would normally see with a 2 volt pre-amp, BUT at the same time it lowers the level of any noise that may be picked up by the wires, effectively reducing the noise level.

How much reduction? In theory 4v outputs should give you a 3db better noise reduction. Does it matter? I guess that depends on how much noise your wires are picking up and whether you can tell the difference between 90dB signal-to-noise or 93dB signal to noise (while driving a car with 30dB signal-to noise).

 

Thanks for the good info, guys. So in your opinions, the Alpine deck qualifies as a good enough HU to not worry about the voltage difference?

modifry - i like quality audio, but certainly don't claim to have audiophile listening abilities, which, as you hint, would be damn hard anyways in a lightweight convertible.

What noise ratio should i be looking at for the amp?