With the Aleph 5 I had great results with an ARC LS-2B modified by GNS. It is a hybrid design using a single 6922 tube. I was using Silverline SR-17 monitors at the time. I'm sorry, but I recently sold my LS-2B and all the paperwork that went with it so I can't tell you what the output impedence was for sure, but I think it was 24 for the balanced outputs. I also tried the Aleph 5 with my Cary SLP-50a which I believe has a lesser output. If I'm recalling correctly I think I didn't like the results with that combo....a bit flat and soft sounding as I recall, when compared to the LS2B. I also seem to recall someone else recommending that same Cary preamp with the Aleph5, and could not imagine why. BUT That same Cary SLP-50A is PURE MAGIC with my SET amps, so go figure. Synergy, synergy, synergy. I also tried the Aleph 5 with Klipsch Heresy speakers and enjoyed that combination as well. The Silverline's were really wonderful though. I only kept the Aleph 5 for a few months though as I ultimately missed tubes. One other detail I recall being surprised by was that it did not seem to put out much muscle for its 60wpc rating. In swapping over the Aleph 5 in my work system for a pair of 35W Quicksilver MiniMites it seemed like the MiniMites had more punch than the Aleph 5 at almost half the power. Regardless, the Aleph 5 was a really impressive SS amp.
Good luck!
Marco
Good luck!
Marco