ok i have some old german old schhol acid techno/acid trance/acid hard trance and acidcore records in my collection so if i could recommended something it would be:

1. Go and check all early Andreas Krämer sthuf better know with Markus Schneider like Junk Project.
Check his first label named: Thai Records.

2. Check Dance Ecstasy 2001 and 100% Acidiferous label.
Both were PCP sublabels with a lot acid influences.

3. If you love sthuf like Brain records defo check all Casseopaya releases and artists on Made In Frankfurt and Ipcress Communications label

4. if you like old hard trance and rave records with acid bassline go and check releases from:
Adam & Eve records, Cybertronic Records, Fog Area, Frankfurt Beat Productions, Generator, Important Records + Important Raver sublabel, Harthouse, Influence Recordings, Rough Technology, Sound Of The Bomb, Suck Me Plasma, Time Unlimited, Trigger, United Ravers Records and more more more.

There is a lot (hundrets?) unknown, small and not well known labels from years 1992-97 in germany, hollaand, itally and spain.
Go and check your local second-hand or.... ebay :)

5. Tesseract Records

6. More labels with acid hardcore and acid techno influences: Labworks, Cenobite Records (dutch label), DJ.Ungle Fever, Kill Out Recordings (uk), Millenium Records or maybe Zodiak Commune.

7. Go and studing www.discogs.com >> its a mine of knowledge :)