I'm not so sure about the less popular than Leak bit. They were heavily advertised, widely available, got good reviews and were eventually sold by Comet. They were made for about 7 years and I get the impression they sold in large quantities. Quite how they compare with Stereo 70/Delta 70 in total numbers sold I couldn't say but I would guess similar. The Leak amps were made for approx 8-9 years, covering both the original and delta versions, but the Delta 75 receiver for only around 3-4 years and, although IMHO the Delta 75 is probably Leaks finest hour in solid state units, I don't think they sold particularly well. I see maybe 10 amps and tuners for every 75 receiver from Leak. The 2000 units were spoiled by the truly awful sounding amplifiers/amplifier sections of receivers but both the amps and tuners in the 2000 series were very technically advanced for the time and in fact just as high tech (maybe more so even) as Japanese units.
For a comparatively small UK company to have designed and developed such a complicated, fine performing, compact and stylish (B & O influenced maybe?) unit at the time (released 1973) seems impressive to me. They were not without their faults though... a few of which were proper "howlers", some other design choices which no doubt seemed a good idea at the time but came back to bite them.
