For those who upgraded hifi audio: Quality of OEM HU? Where to put BT controller?

[IMS M3]

For those who have upgraded the hifi 676 audio system with good quality speakers/amp/DSP: have you noticed that the OEM head unit is the limiting factor? I had Audiofrog GB10, GB40, GS8ND2 underseats, GS25 rears, and GS12 trunk sub installed with Helix V TWELVE DSP amp in my 2011 E92 M3. All new actively wired, sound deadening added and DSP professionally tuned.

Using known test tracks through Apple Music at CD-quality bitrate connected through USB to the OEM head unit, sound is good but somewhat harsh and not as clear as it should be. When sending signal directly to the amp via optical from a mobile player with good DAC, sound quality is improved.

Anyone else notice this? Is it the DAC in the HU?

I was planning to install Helix’s Bluetooth module to bypass the HU. If so, where do people install the volume controller? I’d rather not cut the center console to install below the iDrive controller, but the ashtray area seems too small and far away.

Thanks so much for the help.

https://www.audiotec-fischer.de/en/h...ssories/hec-bt

[Thumbie]

You are streaming the music from your iphone or the songs are downloaded?

[tdott]

What inputs to the amp are you using?

Hopefully not high level.

[IMS M3]

Originally Posted by Thumbie

You are streaming the music from your iphone or the songs are downloaded?

Streaming from Apple Music on my iPhone via USB to the OEM head unit (it's a 2011 with the USB receptacle). Sound quality is set to lossless (16-bit/44.1 kHz ALAC) or better.

Originally Posted by tdott

What inputs to the amp are you using?

Hopefully not high level.

Not entirely sure. I believe it's simply what's coming out of the OEM head unit to the Helix V TWELVE amp/DSP. Volume control is through the head unit.

[Thumbie]

Hmm...well TBH I did not know you could send apple music lossless through USB. I receive my car in a week and will try this. Saves me from buying a Bluetooth dongle haha.

Also, I really haven't heard many complaints about quality loss through the factory HU, only when sending music through the AUX. Even then, much of that complaint is based on perception (someone noticed it once and now everyone acts like it sounds terrible, when in reality it's fine for 75% of listeners)

Of course, neither of my two statements really help you, sorry. Maybe there is an issues somewhere? A bad connection? Bad ground? Really not sure here.

[IMS M3]

Had the Helix bluetooth module installed today. Definite improvement in audio quality... now it's where I was expecting it from the start.

I'll do a writeup on everything at some point for the benefit of the community. If anyone has any qs, feel free to ask here or PM me.

[TboneS54]

I use the technic harness so it's low level (5v iirc). I also have a 2011.5 so I can play .wav files through the CIC.

Quality is perfect.

ARC Audio xdi amp, CDT speakers.