Not sure he's underground (and more acid than IDM), but Ceephax Acid Crew is always excellent. I especially recommend the releases Acid Quakers 1000, Exidy Tours, World Dissolver, and Cro Magnox (but really, look up any of his music videos on YouTube. They're insanely fun)
For more downtempo or glitchy type stuff, check out:
Lanark Artefax - Whities 011 (Touch Absence is a track that shouldn't be missed. The music video is good too)
Proem - Socially Inept
Lusine - Condensed (the track Rushhour is superb)
Grischa Lichtenberger - Graviton - cx (rigid transmission)
Oneohtrix Point Never - Garden of Delete
Albums not on Bandcamp worth checking out:
Access to Arasaka - void();
Richard Devine - Asect:Dsect
You probably know these, bit worth mentioning:
Venetian Snares - "Hospitality" and "Rossz Csillag Alatt Született"
Autechre - Oversteps
Alva Noto - "Xerrox" series
Just copped this the other week! Good record.
One of my favourite tracks of the last few years, such great production
I know a few of the others (used to love that Proem album, big Alva Noto fan), will check the rest. Thanks!
* Analogical force
https://analogicalforce.bandcamp.com
* Further electronix
https://furthurelectronix.bandcamp.com/
* Touched - quite varied output, some IDM
* CPU records
Here are some more labels from the chilled out side:
* City centre offices
* Morr music
* ~scape
* Kit records
Artists:
* BRAINWALTZERA (big tip!)
* James Shinra
* Cristoph de Babylon
* Doghn
* Bochum Welt
* The Remote Viewer (especially the "black" album, can't remember the name)
* Jan Jelinek (dub IDM sort of)
* Global communication
If you're a fan of the 90s-2000 stuff from SF's SomaFM [1] their playlist is always pretty good, I actually ripped their entire station (back in the early 2000s there was only Groove Salad and maybe 2-3 others) for 6 months and bought pieces here and there as I went along. My favorite was a rare Lloop album, and a remix album of The Irresistible Force's track Nepalese Bliss. I always wanted a vinyl copy of Stryke - Introspection, I already have the CD version, but couldn't find it anywhere, even on Discogs after all these years. I got a bunch of Higher Intelligence Agency stuff, too somewhere in a box.
It's hard to know exactly when IDM turns into Ambient, and where Ambient can cross over to Triphop on that station, but I found a ton of amazing stuff from really niche artists like Global Communication, Mark Pritchard, who eventually got into the same Dubstep sound I was into later on and got his stuff released on one of the most venerates labels at the Time (DeepMedi). He even came from Australia and played at the Dub War nights in NY with Joe Nice.
I actually met Gel-Sol randomly in a chatroom, and he gave me a cut of his album with no strings attached [2] when I recognized his name back when I was an incoming freshman living in the dorms to listen and review while we spoke. I never saw him again after we spent all night talking about EDM/IDM artists we liked and the album ahead of its release. My GF at the time just rolled her eyes and told me I could have just told her I didn't want to hang out instead of making up some elaborate lie to stay in my room all night on the computer.
I just played Few and Far Between while updating this with links and it still puts a smile on my face remembering that night.
Those were crazy fun days that I'm still fond of, especially given where my musical tastes have gone throughout the years spanning/DJ'ng dark deep UK halfstep 140/170BPM and now into Darksynth and Dark Elctro as it doesn't make any sense as I originally come from the chiller, cerebral, calmer IDM ambient side of EDM, too.
Here is another playlist with featured Groove salad tracks to check out [3].
Glad to see the Bandcamp guys checking in, thanks for what you do, guys!