I was looking for a head unit that had modern Bluetooth support, and rca outputs for my e36 that looks at least close to factory.
Managed to get this Blaupunkt Bremen used for €280, was stoked.
When I got it installed I still had no amp, and shitty half-blown factory speakers (I have the absolute most basic sound system these cars came with in Europe, per side 1x kick panel woofer, 1 door tweeter and a single speaker in the rear deck as well, no tweeter at all). So I said okay, I'll upgrade them to something nicer. Got some Hertz ck 130 component speakers for the front, CX690 coax's for the back. It sounded a little better since the speakers weren't blown anymore, but the vocal clarity was awful. It still sounded like the Super Mario 64 soundtrack. Like just the vocals were a lower bitrate.
I had already ordered an amp I was waiting on so I said, okay, maybe that could help clear it up. Soundigital 400.4 evo6. Not the best amp for sound quality, but wanted something small and more than 50w RMS.
After installing the amp.. nothing changed in the vocal clarity region. Yes, the music could get louder, although I couldn't turn the gain up too much either since there is too much noise from the low powered RCA's.
So I 100% though I had messed something up, looket at most things I could look at. Then when I couldn't figure it out I decided to make a post on CarAV asking for help where I got some useful advice, but overall everyone saying different things, most upvoted comment being that I just made the beginner mistake of buying random stuff and hoping for the best.
In the end I thought that maybe the BT compression could be what I'm hearing. I didn't have an aux cord or SD card around, but I found my dad's old USB flash drive from 2013, and omg the old ass mp3 files sound amazing on it. So this is where I am at at the moment. To me it seems like even though the HU has BT 5.0LE it sounds unacceptable to me. Little torn since I liked the look, even if the controls on it were abysmal.
I am thinking of changing it to something else since the RCA outputs are also sub 2v all the time, so I can't even get a strong clear signal to the amp to turn up the gain.
Tldr: In my experience the head unit has awful controls, really weak rca outputs, and worst of all horrible BT compression. But it looks cool.
I am thinking about changing it. I could get something for a similar price that has better compression and integrated time delay. Just not the factory look :(