OK, so it's a decade later than most of these comments, and I obtained a SP-11 MK II, upgraded the caps and wiring, a couple of other "tweaks", and installed a set of 6 circa 1968 German-made Telefunken (cryo treated) 6922 tubes. It is, in a word, beautiful.
ARC SP-11 MkII vs. ARC Ref. 1 & the winner is.....
I recently had the chance to do a direct comparison between the ARC SP-11 MkII and a ARC Ref.1 preamp. I tested the preamp in the same set-up, same vaccum tubes(6DJ8), same CD player and same speakers. At first I thought the ARC Ref. 1 will easily outperformed the "out-dated" ARC SP-11 MkII(1987). But to my surprise, the ARC SP-11 MkII outperformed the ARC Ref. 1 in every ways. For example in male and female vocal, the ARC SP-11 MkII were smooth, full and sounds like a real human vocal. In comparison, the Ref.1 sounds artifical, unnatural, harsh, less body and always sounds like reproduction signal. The SP-11 MkII also matching the Ref.1 in micro/macro dynamic, speed, sound-stage etc......
After 5 hrs. of carefull comparison, I packed the Ref. 1 in its original box, sealed and listed in Audiogon and I never look back...............
After 5 hrs. of carefull comparison, I packed the Ref. 1 in its original box, sealed and listed in Audiogon and I never look back...............