I'd like to add Mp3 CD capability but I want to keep the stock BMW head unit & factory 6-disk CD player intact. Will one of those adapters that fits in the cassette work and then use a portable "Walkman-type" CD/Mp3 player to run the Mp3 CD in? If so, would the sound quality be ok or would it suffer to where I wouldn't want to bother with it in the 1st place? I'm a deaf old fart & my hearing is shot so I'm not aiming for the best sound quality, anything comparable to stock exceeds my hearing range.

Thanks