To say I am not over-whelmed with the Bose system in my 2014 A6 TDI would be an understatement but knowing that source material can have a big impact on audio output quality, I have searched the forums for advice on what is the best medium for audio quality playback. It appears that most digital inputs to the MMI system are limited to 320 kbps and 48kHz sampling. See snagitseven's post at:
This is certainly not as bad as a highly compressed MP3 on an iPod but it is not full CD resolution either. Obviously playing a music CD would allow full CD audio but would be limited to 16 bit word length at 44.1kHz sampling. After playing around with various input sources using the same source CD (Chesky's Rebecca Pidgeon, The Raven), I subjectively came to the conclusion that the CD player sounded best of all the inputs I tried. I know nobody wants to play CDs anymore, they are just so 20th century, but this got me to thinking.
Knowing that the DVD standard allows for 192Khz/24 bit resolution PCM audio, and that the DVD player would play audio but not video while the car was in motion (yes I know that can be changed), I wondered if a Music-DVD containing hi-res audio files would sound better than a CD. I made a Music-DVD using Toast 10 (Mac OSX) that contained the Chesky recordings of SaraK's What Matters and Rebeca Pidgeon's Four Marys both recorded as 192kHz/24 bit AIFF files. These uncompressed full resolution files are big so I was only able to get two albums on a DVD. The resulting sound was in my subjective opinion stunningly improved. I won't bore you with all the audiophile verbiage because I am not an audiophile.
I would note that the industry asserts that good audio can't be heard in a car because of all the noise and the small and difficult acoustic environment. Balderdash! My Acura sounds a ton better than the Bose junk in our Audis and it plays a DVD-Audio disk that sounds quite good, and the Lexus standard audio system absolutely buries the Audi Bose. There is just no excuse for a high end car to have such a mediocre sound system. But, the high-Rez sound I heard with the Music DVD was strikingly better than anything I had heard out of the system before. Unfortunately it also betrayed the faults of the system like the thumping one note bass that is rendered from any music that has any kind of bass in it.
Having heard the improvement offered by 192/24 files, I made a similar disk with files encoded at 96/24. I could not detect a difference in sound from the 192/24 encoded disk. I did not pursue this further but it is possible that 48/24 would sound as good. It's possible that the 24bit encoding is making the biggest difference; and it's also possible that the audio decoding in the DVD section is just better. More possibilities could be explored here.
In the near future I plan to make a disk using ALAC (lossless encoding) files to compress the file size further. If this works it should be possible to put the equivalent of 8-10 albums of music on a single DVD which is a reasonable size for a playlist. If ALAC at 48/24 sounds good enough, some fairly long playlists could be saved onto a DVD. I hate going back to physical media and all its disadvantages but I am going to make a few DVDs and use them on long trips. I don't mind the Bose for trips around town but for a long days on the highway, I'd prefer the sound that I heard coming from the hi-res encoded DVDs.
I'd be interested in know if anyone else has a better solution. Specifically has anyone managed to get hi-res audio sources into the system any other way? I couldn't do it using the USB and Chip inputs. The screen appeared to read the files and often got the title right but said the track couldn't be played in one way or another--usually track error. One thing I also want to try is a small portable Hi-Rez audio player (eg. FiiO X5) plugged into the analog stereo audio-in jack using 3.5 mm pin or RCA jack output from the player. It could be that good analog signal in will produce a favorable audio output. Has anyone tried this? How good is the analog audio in? If it is good a small player would be preferable to DVDs for sure.
All things considered, I now realize that i should have sprung for the B&O audio upgrade. I will probably be going for an aftermarket audio upgrade. In the meanwhile, DVD encoded music will have to suffice.
Sorry for the long post but I thought there might be someone else out there who either wanted to know how to get better audio out of the system or who had a better way to do that.