I've been trying to figure this out and figured I would put it out there for the gurus. Is there any real difference between speaker level and line level signals other than the voltage and the ability to drive a speaker level load (2-4 ohms vs 100ish or whatever for an amp).

I guess what I'm really asking is this:

Say we have a headunit that puts out 25 watts at 4 ohms. which by my calculation would be 10 volts. Now lets take that and plug it into an amp that can handle 10 volts (or split into two amps for 5 each). Is this fine to do or would it not work well?

Is this fine to do or would it not work well?

Will not work well.

Is this fine to do or would it not work well?

Will not work well.

I figured that, but do you have any insight why?

I know I read one time an spl competitor used a small 2 channel amp as a line driver simply because they needed the voltage because it was split between so many amps (rather than using Y cables) but that's SPL so obviously signal quality isnt too paramount in that case.

Big difference between a headunit and a small 2 channel amp....pretty simple garbage in garbage out.

Big difference between a headunit and a small 2 channel amp....pretty simple garbage in garbage out.

thats cut and dry

So theoretically if the headunit's amplifier was "perfect" sounding it would work the same as the preouts, just with higher voltage, but what you guys are saying is it doesn't work because the amp sections in headunits are junk.

I guess what I'm saying at this point is that I know it will work like crap, but now I'm asking if I have my theory correct.

The question is, why?

Unless you're running a van-full of amps like you described above, there's really no need for very high preout voltages.

Heck, there's a fair amount of people in home audio that run absolutely no active preamplification between the transport/DAC and the power amplifiers, as long as the input impedances work out and cable capacitance isn't a factor there's really no need for anything more

Well, I was going to see if it was a viable option for my factory integration install. I have an 05 magnum with factory navigation that I want to keep. It has one stereo set of speaker level outputs coming off the headunit and I was going to see if it was a good choice to take that and split it into 3 plugs for each channel (im planning on an active two with with no rear fill and of course a substage). I wanted to see if this would be viable rather than using a LOC and splitting(or using passthrough if the amps would have it). So I know I don' need 15V signal lines, but I figure bypassing a LOC is always good if possible since some cut bass bad and have various other problems.

i dont know of very many amps that can handle a 10watt input.

and if there are any im sure there not gonna be SQ amps.

But, that will get split 3 ways so each amp will have 1/3 the total voltage (right?)

It's hovering around 0 degrees in MN right now, but once it warms up maybe I'll try to rig something up with stuff I have lying around and see how it works.

ah thats right i forget that you said you were gonna run thre amps,

We did it with LP amps back in the day, but then you did not have high power HUs either and you could not turn it up that far because of distortion even with a good HU. But LP liked lots of input and some people are not so worried about quality, and you did not have to worry about line noise that way. I think pioneer HU with the worst line level ever were the ones I did that on. Way better to get a line driver like a LP PA2 back then. It depends on how the HU reacts to that high ohm load, and how clean it is. I would use a knockdown or the products they now have for that. I've had knockdowns that would let a lot of power through if you turned them up, but hey why not try it and see. Just don't blow the inputs of the amps.