On early Melchior there is a lot of korg groove boxes all over his sound.
Imho mastering is not where the magic happens. Mastering is just the icing on the cake.
With the years I also became aware that many of these artists living in germany where and are indeed using stuff from german manufacturers like Vermona, Acidlab, Jomox and MFB. Sometimes people tend to forget about this.
From what I know:
Bruno pronsato = jomox 888
Ricardo = jomox 999, vermona drm1 mkii (blue version), acidlab miami, mfb 522 and tanzbar
Melchior = korg ESX, EMX, ER-1
If you can watch the Melchior slices interview. Korg groove box orgy. At that time he had his stuff going into a soundcraft ghost desk, that sure helps.
I'm pretty sure that all have used the same stuff that everybody does, they just do it with their own taste and process it better.
I got some of these, and guess what I still suck compared to them