2005 GM TNR Low Level Audio Out split = degrade?

To add an amp for a subwoofer, I want to splice into the Low Level Audio Output signals in between the GM factory touch screen navigation radio (TNR) and the separate factory Bose amp. The factory TNR and Bose are not Luxury (ie not Y91). I want to send the full range low level signal of all four channels (LF, RF, LR, RR) to the new subwoofer amp, rather than using a LOC on the pre amplified subwoofer outs from the Bose. However, I'm concerned about potential signal lose to the original Bose amplifier, due to having Y split the low level audio outputs in order to feed both amplifiers.   Should I be concerned? What would be the best practice?

Use line output converter.

i am an idiot wrote: Use line output converter.

I assume you mean using some speaker wires? There are no speaker wires coming out of the head unit, only low level audio (line outs). The speaker wires come out of the Bose amp, already crossed over and frequency cut. It seems to me like using the LOC would be a step backward... converting high level speaker wires that have already been converted from low level audio signals... back to low level audio signals again. I'd rather just send the new amp low level audio signals.   The new amp doesn't have RCA inputs either, just wire harness connections. I'd have to convert from RCA to harness connections anyway, creating more connections that introduce noise and signal loss. There doesn't appear to be much advantage to me using an LOC, in this case. Unless there is something I don't yet understand, which is entirely possible.   My concern in this question though is what are the ramifications of splitting the low level audio signals.   Some aftermarket amps do this, with pass through line in line out arrangements. That, in effect, is a Y split, which is what I'm considering with my headunit's existing low level audio outs.

I did the same on my 2013 impala that had the bose system. I located the low audio signal input that feed the bose amp and cut/soldered spice two sets of RCAs and feed my amp. Worked great. Although, I used the optional "line output" on my 4ch amp to feed my sub amp. Worked great. No need to use a LOC or splitter . The stock OEM unit fed the bose amp with full range low voltage sound and the bose amp separated the signals to 6ch output. Just locate the low audio input signal and directly tie in some RCAs to feed the amp. You can also just run new speaker wire to bose amp and disconnect output side and tie together from new amp, no need to run new wire all the way up front to door speakers.Go BIG or go Home                                    it might not be broke, but lets fix it anyway

TalarChevy... Thank you for your report! Did your Chevy head unit also have a "mute" wire? My GM head unit has a "Radio Mute" wire, and it goes to my main amp (GM amp). However, my add on Sub amp does not have a provision for a "Mute" wire.   My current best guess in this scenario is that when the Radio commands "mute", my main amp will be silenced, but my sub amp won't. I was curious if you encountered this situation in your installation? What do other installers and do it yourselfers do when only adding a sub amp using the full range low level line outputs from the head directly from the head unit, instead of converting preprocessed high level speaker wires?

My stock head unit still had full functionality of its features, mute, steering wheel controls, etc. I only had one bose amp to bypass. The bose amps turn off and on through GM data(I forget what it's proper name is) and stills mute, etc. Are you sure the wire you're looking at is confirmed radio mute? I had no problems with setup when I bypassed it except for the louder amplified GM door chimes. You can lower the chime volume through the DIC control menu. By the way, I first bypassed the bose system and just added my JL audio 4ch to power the stock bose speakers and they sounded great. Then I eventually installed Focal components in doors, but the bose performed well.Go BIG or go Home                                    it might not be broke, but lets fix it anyway

I apologize, I re read your post. Yes no matter what, when you mute the stock GM head unit, it will mute the low voltage input signal feeding your bose amp and the low voltage signal you spliced into feeding your sub amp. (same signal) just be sure you are feeding the sub amp off of the low voltage input feeding the Bose amp. If you find the sub output feeding the stock bose subwoofer and use that to feed your sub amp, then yes you will need to use a high quality LOC.Go BIG or go Home                                    it might not be broke, but lets fix it anyway

FWIW splitting an RCA line level should not degrade the signal any more than the connections and the wire itself. This is because the amps have a very high input impedance. If you went crazy splitting out to many amps, then yes, the effective impedance could drop enough to start pulling at the signals amplitude, which I imagine would cause a horrid distortion. There is the possibility of picking up noise, especially if the run is long and the wires are unshielded.Build a man a fire, he keeps warm for a day. Set a man on fire he stays warm for life!

Knudsen...Thank you for the feedback on splitting low level signal lines. It sounds like just one split for a very short run shouldn't noticeably degrade signal. TalarChevy... Thank you for your continued feedback and guidance on what you have done. My chevy is a bit older than your chevy, so I imagine that there are a few differences, but in general your feedback is helping me put it all together in my head... before splicing wires. Because of the door chime issue, and because of the rear seat audio control issue, I've been thinking about NOT using the low level audio signals to the original Bose amp, and instead using a high quality LOC on the high level outputs to the original Bose sub, in order to get some signal into the add on sub. This would avoid any issue with chimes, because I presume that the Bose amp filters the chime inputs from the head unit out of the subwoofer output signal. The only problem with using the Bose sub out signals is that they are already frequency cut, and that cut off may be a lot higher than the frequencies my supplemental sub would be capable of reproducing. So that is an issue... Thoughts?

i am an idiot wrote: Use line output converter.

I'm beginning (slowly) to see the real value in this advice!    Can you elaborate more on your reasoning, given the concerns that have been raised in this thread since my original post.