"No Signal" Then bass mostly gone

[jfandl]

Last week I was driving and came up to a stop light when sound stopped and the display showed "No Signal". Idrive rebooted and afterwards the audio sound changed. There is now very little bass and I have to turn up the volume a lot more than in the past.

2014 F15 with Top Fi 688 HK Audio system
I tested with ISTA+ and confirmed all 15 speakers respond to sound but it still sounds lame now. I just rented a 2020 330 and realized just how bad my sound is compared to it now when mine was always awesome. Since all speakers produce sound, does anyone know how to troubleshoot further? It seems like the power output was seriously reduced but it does work. I pulled the battery for 10+ minutes, cleared out any codes (no audio codes) but I'm stuck where to go next. Any ideas?

[Ascotgrun]

Bad amplifier would be my first guess. Can't hurt to try the free stuff first like pulling it and making sure none of the connections are loose or corroded/dirty.

I would be hesitant to buy a used replacement. Maybe one of the upgraded offerings from Bimmertech or Fischer etc would be the way to.

[jfandl]

Originally Posted by Ascotgrun

Bad amplifier would be my first guess. Can't hurt to try the free stuff first like pulling it and making sure none of the connections are loose or corroded/dirty.

I would be hesitant to buy a used replacement. Maybe one of the upgraded offerings from Bimmertech or Fischer etc would be the way to.

I already removed and re-seated all the connections and the MOST bus fiber with no luck. This is a replacement Amp that I had to buy 1.0 years ago (Used $600) because I got hit with the dreaded sunroof leak that floods the BMW amps that are mounted on the rear quarter panel. I installed a water shield after that incident. This time the Amp was dry with no recent rain in the area so I know it isn't water damaged again.

Thanks for the tip on the Bimmertech & Fischer unfortunately they only sell amps to replace the basic BMW sound system (Bimmertech) or older E90 style (Fischer). The option 688 HIFI system I have is 14 channel + Sub. I haven't found any aftermarket options yet.

[Ascotgrun]

Pretty sure I have seen HK systems upgraded with Fischer. I think there needed to be a MOST adapter also. There is a lengthy thread that delves into upgrading the audio. Not technically what you want to do but the info should still be helpful.

I have HK also and if my amp died I wouldn't be buying new from BMW, that's for sure.

[Ascotgrun]

"Bimmertech makes a rebranded helix/match amp/dsp. If you don't have the HK system it it plug and play with their harness. If you have the HK system you will need the Sdmi25, bit dmi, or a mobridge converter."

This is a post from member bmwx1sq who has done quite extensive audio modifications to their car. It is a good starting point of research. I was mistaken in saying it was Fischer earlier.

I don't know what all that will cost, but it would be preferable, to me anyway, to paying BMW prices for a new HK amp.