[100percentjake]

The car
2008 E92, Hi-Fi sound system, MULF aux, stock amp, stock head unit, CCC, AlphaOne full speaker upgrade.

The Problem
The aux in sounds atrocious. MP3 CDs/Normal CDs sound absolutely phenomenal, but aux in is scratchy and half the volume.

What I've tried
About 15 different sources. iPhone through Lightning -> 3.5mm jack, FiiO headphone amp, Wolfson DAC iPod, various bluetooth adapters. All of these sources sound phenomenal through headphones.

I also tried ditching the MULF aux port and coded in the second aux port on the back of the head unit and wired a 3.5mm jack directly in. No dice. I can load up the exact same file on an MP3 CD and my phone, press play on the phone and CD at the same time and when I switch from the CD to the phone the volume drops by half, seemingly, and if I try to turn it back up it starts clipping well before it gets to a decent level.

All of this has been made far more noticeable by the (frankly excellent) Bimmertech AlphaOne speaker upgrade.

I have also tried volume on my sources at full, or at 80%, or at less.

There does not seem to be any setting anywhere in the CCC for volume for different sources.

The Hi-Fi EQ is pretty useless.

Confusion

How does the hi-fi utilize the MOST bus? Is there a digital way to get audio into the system without utilizing any of the garbage analog-to-digital signal processing that seems to be destroying audio quality?

Products like the AVIN MOST adapter (see below) describe their Aux -> MOST adapter as being "for logic7 only", whereas other such products make no such distinction.

Potential fix (expensive): GROM MST4 ($289)

https://gromaudio.com/store/most_ada..._optional.html

Aux, bluetooth, and USB audio transport to MOSTbus.

Claims compatibility with any car with MP3 CDC compatibility.

Potential fix (less expensive): MR12VOLT MOST adapter

https://www.mr12volt.com/products/p600-lp1601bm

Same as above, but cheaper.


Potential fix (cheap): AVIN MOST box ($119)

https://avinusa.com/most-fiber-optic...7-e88-e89.html

Same as above, but the verbiage is... strange. Seems like they're claiming it *only* works with H/K or Logic7.

Probably the ultimate fix (wildly expensive): Mr12volt Carplay box ($429)

https://www.mr12volt.com/collections...ts/p2000-cccmd

Full digital carry of wired or wireless carplay/Android auto or bluetooth, with built in DSP (looks to be just EQ? no time delay functions?)

Thoughts

Obviously I am very tempted by the AVIN MOST box (various clones/unbranded versions available on Aliexpress for similar prices) but the roll of the dice there seems to be the quality of the analog to digital conversion. I'm not really sure how something as simple as "sample this analog signal and encode it as 1s and 0s" can be messed up but... BMW clearly shows that it is possible with the trash quality of the MILF and quadlock aux ports.

That MR12Volt carplay box is super tempting. I have a carplay box in my car, but the audio comes through aux so... it still sounds like roasted garbage, which is a big part of why I'm looking for a solution here.

If anyone has recent experience with AUX -> MOST adapters in S767A Hifi CCC cars I'd like to hear it. Especially if there are any audiophiles in the house.

[ctuna]

A big part of your problem is you still have the crappy Hi Fi amp.
(If I am reading your response right)
Mr12volt make a simple and a complex interface that uses
the Most Bus for sound and not the Aux.

I only have the Pro Radio and am using there simple interface
which used to cost under 150 and the sound is the same as
from the CD player with the same files.

There new interface for idrive with carplay and android seems
like a good thing if you need those. It's about the only company
that does Most interface that I know of . Used to be Dension.

Hi Fi amp runs out of power at 1/2 volume and starts to distort.

Hi Fi is option 676 not 767 which I don't believe exists.

Avin Most Box if for interfacing a Logic 7 head unit to and aftermarket amp
without having to reprogram the Head unit for Hi Fi . I don't see how that will
help you.

I also have an aftermarket amp and speakers .
Jl 600/6 and morel/jehnerts. The hi fi system is already crap and the
crappiest part is the amp . All the BMW amps are crap.

[Captain Buumer]

+1 ctuna.

to sum up.

AUX - avoid. Just imagine your car doesn't have it.

MOST integration - only option. Basically another unit added to fiber loop.

Options:
1) Mr12volt
2) Dension 500S BT
3) Something similar

[100percentjake]

But the amp is fine, because CDs sound fine and those are going through the same amp. Unless by "amp" you're referring to something else?

But, yeah, guess I'll look at the MOST options.

I totally had the AVIN box backwards, I thought it was an input not an output, lol.