NaturalOrthodoxy and Silvum, thanks for the posts.
I had to hit my listening notes and dig. For this first bunch, I'd recommend you registering at the Dime a Dozen tracker. It's where I found most of these, if not all of these, live recordings. I wouldn't know where else to go, but I'm sure there are other resources.
75-09-26 sbd - 1 track; 42+ minutes; A- recording - with Gunther Schickert - a true treat to have a recording with GS (GAM; Samtvogel album) in the mix - absolutely blissed out music with moments of heady, kinetic feel and windriding sweep.
76-04-03 FM Paris - "C+"-"B-" sound quality - 1 hour 50 minutes - 3 tracks - very easy listen.
76-11-04 FM BRT-Studio4 - one 47-minute track - "B" sound - solid material ala Timewind.
77-09-23 aud - REALLY nice show - I believe this is the show I used to recommend to everyone who asked.
78-11-16 aud Paris - very good "B+" to "A-" recording - great show - lots of movement - lots of good ideas that grow into solid tracks and improvisations - HIGHLY recommended.
78-11-18 aud Erathostene - 4 tracks; 2 hours 23 minutes; B to B+ recording; from the "X" tour - the first track is 30+ minutes of Schulze beautifully coaxing a cobra from a basket - there's a spot in the performance where it sounds like his tape machine is malfunctioning and speeding 3Xs too fast, but he pulls it in and makes the next transition feel seamless - good performance and recommended.
if live recordings aren't your thing, as a second option, I'd recommend digging around the La Vie Electronique series. As of today, there are 16 multi-CD sets. These are the couple I'd try first.
Klaus Schulze - La Vie Electronique I 1968-1972 - GREAT sound - "Electric Dream" will jettison you into a nether galaxy - "Gesang Zur Dammerung" is another track beyond wor(l)ds - could never have enough Schulze on organ - once you start, you don't want to walk away from these 3CDs - highly addictive and RECOMMENDED.
Klaus Schulze - La Vie Electronique II 1972-1975 - first disc has a couple tracks riddled with clicking rhythms that are digital in nature, and I find they distract, and detract, from everything else; "Study for Philip K.Dick" is incredibly fierce nonetheless - disc 2 is gorgeous, as well as most is of disc 3 - disc 2 and most of disc 3 are from 1973; great year for Schulze.
and this one is not to be missed. Schulze is in the studio.
Far East Family Band - Parallel World 1976 - flat-out amazing psychedelic space reminiscent of a Klaus Schulze involvement with early Tangerine Dream, Ash Ra Tempel, and The Cosmic Jokers; might even have a little Sergius Golowin in it - Japanese fellas doing the Teutonic cosmic dance better than most of the Germans of the golden era - I live to find albums like this.
I'd second Silvum's recommendation to try anything and everything through 1979 or 1980, but I continue to give everything he does a try. He did some recordings with Lisa Gerrard (Dead Can Dance) around 2008 (?), and while the official album was so-so, the supporting tour had moments of brilliance. I think it was 2007 when he did an album called Kontinuum, and there is some nice material there as well. Like Moebius and Roedelius, Schulze still has the touch. It might only be a track or two per album, but generally, it's there. While he is a tool master, I feel it would be more often if he wasn't such a tech nut. His ideas can be muddled by screwing with inappropriate tools.