Underground Resistance and Unit Moebius are pretty much all you need. There are torrents on demonoid with the complete discographies of both labels, and both are pretty much
the sound of awesome electronic music. A lot of detroit stuff, especially Jeff Mills, is worth getting.
In my opinion, DREXCIYA is the best electronic musician to come out of the 90's, get all of his (by "His", I mean Stinson's) stuff and his side projects.
And of course, one of my favorite albums of all time is the 90's classic Photek's "Modus Operandi".
As for Amp, I love it, nostalgically.. WipEout XL, mainstream rave culture, whee! Anyway I have 21 episodes of AMP (47 minutes each) on dvd now. There's a torrent for it on kickasstorrents. Fluke - Atom Bomb pretty much sums up 90's electronic music for me.
http://www.youtube.com/watch?v=11Nq6PzY0xA
A lot of genres, like d'n'b, seemed to have peaked in the 90's. I remember when I first got into MP3's, there'd just be folder after folder of awesome electronic stuff. Modus Operandi took like 3 hours to complete back in 1999! But it was worth it.
Anyway, I am in the process of getting rid of all my cd's/tapes/etc, except for a few J-Indie bands and some discographies (Jandek, Sun City Girls), some modern classical... and I'm keeping all my electronic stuff (this includes electroacoustic improv). 95% of what I've listened to in the past year is electronic-based. So, yeah, I'm pretty much going to exclusively devote my listening to electronic music, probably for the rest of my life... occasionally popping in a Fall or Captain Beefheart album, of course, for old time's sake.