I have a small, 120 watt amp to power an 8" subwoofer that I am installing in the trunk. On a (long) past vehicle I powered this setup from a power lead from the head unit, but my current head unit lacks an auxiliary power output. I see that there is a Bose amp mounted on the roof of the trunk and I was wondering if I could tap the power going to that to run this second amp.

 

I would say just go with normal amp powering technique(from the Battery) if the power is coming straight from the car battery to that bose amp and it has a fuse i dont see why that would hurt. are you trying to avoid running a power wire to the amp? I feel like it would kind of be a waste to do all that work for a 120w amp,my opinion.

 

Trying to avoid running a wire...but more trying to avoid having an amp that is always on. Under my previous setup, it was only on when the head unit was on.

 

most amps have a signal lead/trigger that you are supposed to connect to an ignition/accessory line. Also, running a direct line from your battery is never a bad thing. You'll be thankful you did in about month after you have everything wired up and are not satisified with the output you're getting from your 8" sub.

there are a ton of threads in our stereo/electronics subforum that covers all of this stuff. I'm assuming that's where you figured out how to tap into the bose amp for line level inputs into your sub's amp...

 

The remote (REM on an amp) wire in the head unit (the blue wire with a white stripe) is the wire that controls the amp turning on only when the head unit or stereo is on if this is not installed into the amp then that will result in the amp staying on all the time while connnected to the battery.

 

I tap a 400W amp direct to the bose amp power with no problem..
same for the REM source..u have 2 wire u can pick.. i forget the color so search..

Later on, i upgraded to bigger sub and amp and i ran the power from the battery...