2013 (pre-facelift) B&O seems to have "lost" some sound (?!)

[LawDawg]

So I have a 2013 S6 with the B&O. Because the bass sucks, I installed a JL Audio 8W3V3-4 in the place of the stock B&O amp in the rear deck box (box moved to the tire well in '14+).

So after the car was at the dealership getting unrelated work done, the systems kinda sounds shit. The bass doesn't seem to hit as hard, and the mid and treble doesn't sound as "bright." I'm almost certain this isn't placebo effect or anything. I did an output test with my VCDS and all the speakers made the noise, so I know they're all there. I also scanned for faults, and the only ones I'm seeing on the sound system are the 4 ANC microphones that I disconnected at the MOST amplifier. So...

(1) Can a SVC sub like the JL 8W3 "kinda" break, or is it a work/doesn't work thing?
(2) There are two amps for the '13 B&O system, correct? ICE and MOST? Can one of them be toast while the other still works, and thus the system will still play at a lower performance?

Any other ideas?

[gk1]

Did you put a microsub or something like that with it's own amp/box?

If the issue is just bass related to the new box, then check if all the connections are still ok. Power, ground, signal.
If it is all your sound that has issues (highs and lows, all speakers) then it is a bit more difficult to ascertain. Maybe need some test files with sweeps or a very well known musical source.
Also might simply want to check the basic bass/treble setting in MMI. Sometimes when work is done they reset or change it from what you had.
Perhaps the B&O amp is failing?

[magn2o]

Do you know if the dealership updated your MMI firmware?

[LawDawg]

Did you put a microsub or something like that with it's own amp/box?

If the issue is just bass related to the new box, then check if all the connections are still ok. Power, ground, signal.
If it is all your sound that has issues (highs and lows, all speakers) then it is a bit more difficult to ascertain. Maybe need some test files with sweeps or a very well known musical source.
Also might simply want to check the basic bass/treble setting in MMI. Sometimes when work is done they reset or change it from what you had.
Perhaps the B&O amp is failing?

It's just a JL Audio 8W3 in place of the B&O sub in the stock location. Can an amp "begin to fail" or is it just a work/not work situation? I believe there are two B&O amps in this year, a MOST amp and an ICE Power amp. Could one be toast and yet signal is still getting to the speakers (albeit un-amplified) such that each speaker is still playing, but at a lower power level?

I put the sub in 2019, so it's been fine so far. All of the sound settings are as they were. I cleared all my codes, drove my kids to school and then ran VCDS again, and nothing related to the sound system showed up, apart from the ANC microphones which I disconnected 3 years ago.

Do you know if the dealership updated your MMI firmware?

I don't believe so. I updated the maps and MMI with an SD card bought from a guy on the forums, but that was in '21 or '22. The dealership wouldn't have touched it this time. They were replacing sway bar links in the back. The only thing I asked them to do was reset my service interval to make the dash warning go away.

[gk1]

It's just a JL Audio 8W3 in place of the B&O sub in the stock location. Can an amp "begin to fail" or is it just a work/not work situation? I believe there are two B&O amps in this year, a MOST amp and an ICE Power amp. Could one be toast and yet signal is still getting to the speakers (albeit un-amplified) such that each speaker is still playing, but at a lower power level?

I put the sub in 2019, so it's been fine so far. All of the sound settings are as they were. I cleared all my codes, drove my kids to school and then ran VCDS again, and nothing related to the sound system showed up, apart from the ANC microphones which I disconnected 3 years ago.

I don't believe so. I updated the maps and MMI with an SD card bought from a guy on the forums, but that was in '21 or '22. The dealership wouldn't have touched it this time. They were replacing sway bar links in the back. The only thing I asked them to do was reset my service interval to make the dash warning go away.

I'm not sure of the spec of the B&O subwoofer but an incorrect impedance match to the amp could be an issue. But as you said it worked fine for years. (shrug) I am unaware of two amps. The MOST (Media Oriented Systems Transport) is a high-speed multimedia network technology optimized by the automotive industry and would have nothing to do with amplifying the speakers themselves. Only the ICE amp would actually deliver power to the speakers.
I am usually pretty negative and perhaps the techs played it louder than you might normally and damaged something?

[was003]

maybe your sound/sub/surround settings got reset to factory settings?

I tried attaching anything to the factory AMP and turns out the larger the speaker, the quieter the output is (duh), so when attaching directly a 600W, 12" 4Ohm speaker - it barely made any sound at all... ended up using the sub out as a high input to the dedicated amp which then drives the forementioned 12" driver...