Matching preamp for Pass Labs Aleph 5

Last summer I borrowed an Aleph 3 which has an input imedance of 23K Ohm single ended only and had a some difficulty pushing it with Blue Circle BC21 tube preamp.

I greatly enjoyed the sound of the Aleph mated to the BC21 but its inability to crank prevented me from buying it. I felt it did acoustic guitars better than any of the other amps I was comparing it to.

I believe the input impedance of the Aleph 5 is 10K Ohms unbalanced and 25K Ohms balanced. So you'll probably have varying results depending on which preamp you try and whether it is balanced or single ended.

I am using one with a Proceed PRE and am quite happy with the pair. I rotate the Pass out and also use a ARC VT-100 and the PRE works fine with that too. I use the balanced connections on the PRE with both the Pass and the VT.

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

I would suggest th Adcom 750. I think it was GP 750. Very simple Pass design. I had one for a whil, loved it then went with a dac with a volume control. I have the aleph 1.2's. Good luck

Getting in late here, but I use an Audio Research LS-15 run balanced into my Aleph 5. Each of these products can be had for around $1500 on Audiogon, so they also make a nice pair from a price consideration.I auditioned this combo directly against Adcom 750 and it was not close - the ARC was much better - the tubes seem to add some air and bloom to the sound. The audition took place with vandersteen 5's. I own Silverline Sonatas and find this set up to be extremely satisfying - superb soundstaging, natural tonal balance. I can afford more but have not been seriously tempted because I really enjoy the particular synergy of this system.