Test if audio output is high or low?

Yep...can't be general with this topic..depends on the particular system. Bose are low level, even though it uses wires and not RCA cables. The new interface modules for chime retention have RCA's for the bose system.

Sometimes the factory system is low level..but higher voltage then others so splicing on an rca will work, but may not have enough volume..once again, it depends.

And anyone cutting the RCA's off the radios...heres a better idea.  Cut the ends off another set of RCA's and splice those to the factory inputs. Then you can plug the headunit in like a human and not butcher it

My 2 cents.

If you are asking if RCA connectors could be used to send speaker-level signals to speakers, sure.  That used to be a fairly common design.  But if you are asking if you can splice RCA connectors onto a speaker-level output then run that into an amplifier's low-level input to gain some sort of "bass boost," no.  Sure, you could physically DO it, but it would be a really dumb thing to do and would most likely lead to a blown input stage on the amplifier.

Agreed w/ DYohn as well.

In that case an adjustable LOC is the proper way to do it. Sending too much voltage into an amps line level input can't be a good thing.

I would imagine this "bass booster module thing" is preamp level and only boosts specific frequencies and if a professional item should have some kind of curve.

However it is hard for me to tell what this really is as "bass booster module thing" is a bit general..lol

If it is a simple "bass control" that does not boost the bass to the amp. It allows you to adjust the low freqs via a remote knob but does not give any more input. If you unplugged the bass knob while it was adjusted all the way  up the bass level woudn't change.

Is either of these what you are talking about azn?

Good to see you again BTW.

An epicenter is actually a great piece. It boosts specific low freqs to all the speakers (if installed properly) not just the subs. However, that is a quite sophisicated unit.

With an Epi if the music you are playing already has a ton of bass information it doesn't do a thing. But on music in which the original recordings didn't use alot of bass..well at the time systems did not reproduce them like today, it would enhance certain freqs that are barely audible and kind of artifically reproduce them (things like harmonics come into play here).

Now of course if you overdrive the input it can cause problems, like anything else it requires proper installation, setup and user responsibilty. But regardless I would not look at an epicenter as a bass booster thing although in a sense thats what it does. But it is not designed to increase the voltage to the amps input simply to boost the bass if you can understand my description. A basic preamp can do that but once again,improper setup and abuse are the culprit if things blow.

But you can't compare that to running a high level signal into an amp by putting RCA's onto the speaker wires. If your system needed more bass, doing it that way will only cause damage in the longrun. It would be like putting nitro methane in the gas tank of a stock vehicle for more power. Might work for a second...but then expect an explosion.