So I've got the HK option in my Justa and I have to say, it's a pretty decent setup. I also had the HK in my "old" Beemer F30, which had the benefit of a equalizer, which I do miss.
However, I've found a way around that. If you hook your phone (well iphone in my case) via usb, then play spotify, it'll use the equalizer in Spotify. So I go and make sure to use extreme quality on my phone for downloaded stuff and we're golden.
I tested with it plugged in and messing with the EQ, worked a charm.
Now I am a very happy camper (I could pull down the mids a bit as I find in HKs they are always to "bright")