[ctuna]

So you are opening u the Mulf and trying to actually trying to
surgically attach a digital input to the internals?
where adc is analog to digital bus or data
and I2s is a standard bi directional bus standard for digital music.
Basicly you are bypassing the aux to get a direct digital input to the
mulf but doesn't the usb do that?

[Stream]

Ctuna, you are right, I want to cut aux input and it's ADC, and connect i2s output of pcm2706 to i2s bus of mulf. I'm not sure it would work, though

Usb is another story. Sometimes I (or my passenger) want to listen music from iphone and it would be great to have airplay support. And yes, we can wire up airport express to aux in, but then we have dac- adc - dac - adc conversion.

[ctuna]

Did you see this
https://www.alexwhittemore.com/more-...is-bmw-module/

Yes it would be nice to get rid of multiple conversions since
the quality is only good as the weakest one.

And the aux seems weak at least in my car.

[Varjo]

Originally Posted by Stream

Mulf2 and mulf2h have aux in which works through ADC. There is I2s bus between ADC and MOST-bus transmitter. So you can use any source with i2s output. I'm planning to mate airplay device (air enabler) and "usb to i2s" transport (based on pcm 2706). I'll report if it will works or not.

This is extremely interesting. While having a higher quality DAC has helped, it's obviously not ideal to convert to analogue only to convert back to digital again... please report your progress; I'm dying for an update!

[fackamato]

This is an interesting thread.

Is converting to analog and back to digital again really that much better than just streaming over bluetooth?

I can't imagine the noise floor or dynamic range be any better on analog vs BT. Sure, BT compresses the signal, but it wouldn't introduce hiss or raise the noise floor.

Did you do any measurements?

[Asonchadwick]

So best thing to do here is to buy a grom unit that has usb otg input and plug in a cell phone. Store touch screen cell phone on dash someplace and use that hardwired. This works for me with my Kenwood in my saturn and lemme tell you the sound is way better than by even with aptx. Not exactly sure what the bmw decodes at though anyone know the sampling rate and bit depth??? I suspect its 16/44 so obviously no high res here but maybe cd quality then.

Secondly i would then get a most to optical converter and add a dsp and amps namely the 12 channel mini dsp.

[ctuna]

The Inputs on such units as the Helix DSP/amps are of higher
quality than the aux on the stock head unit and I believe also
offer optical or digital Inputs. Dension I thought was the higher
quality aftermarket unit that also gives some display on the idrive
not so much on the pro head unit.

[Asonchadwick]

Come to think of it the grom and the dension do the same thing supposedly but i honestly do not know if either if them can stream from say tidal. I assume they can and if so then the grom is significantly cheaper and has built in bt audio streaming even though its not very good quality. I have several cell phones that can all do usb otg and i should be able to just plug into the grom via usb and hit play on tidal and music will go my logic 7 dsp amp right?

[ctuna]

The Dension gateway 500 s bt has bluetooth streaming A2DP.
built in its not and add on how well it works I don't know.
It also has USB.