Pass Aleph 3 or 5 for Proac 1sc

I would definitely pony up for the aleph 5 with the 1sc's. I heard a demo setup with the aleph 3 and some 1sc's. The system could be turned up to reasonable quiet listening levels but no further because it would clip. For a preamp I would go with an adcom 750 if you want to save money. I had one on my aleph 2 monoblocks and found it was a very nice combinatino. Later I substituted an Aleph P and found around a 10% improvement. The Aleph on Aleph combination emphasizes the ultra-quiet distortion free nature of the pass line. If you are CD only I would recommend you go with a cd direct output from a wadia, sony or resolution audio cd player. Those players have variable outs that will feed an amplifier. One problem with adding a tube preamp to an aleph amp setup is that it takes away some of this ultra-quiet quality. I tried a current model audible illusions modulus 3a & found I preferred the passive mode adcom 750. The 3a threw in too much noise.

If you're inclined to use a passive preamp with Aleph 3/5, let me say that I've used a 10K ohm passive with Aleph 3, despite only 23K ohms input impedance for the Pass amp, and it worked beautifully. Nelson Pass confirmed that others have said the same. Better still: a CD player with a good output stage straight into an Aleph 3/5. Aleph 5 does have balanced input, Aleph 3 doesn't. While the Adcom in passive mode may be quite good, it's easy to have a better purely passive preamp, if only through better hardware and less switches in the signal path. There's a Go preamp for sale on Audiogon right now, unless it's sold, which sounds like the best commercial unit I've heard of: it has Shallco stepped attenuators and the steps are 1 db, which is rare.

I currently have an Aleph 3 driving ProAc 1scs and ProAC 2.5s. The combination sounds very good with the 1sc and even better with the 2.5s. My room is about 12x15 and I listen mostly to Jazz so I don't drive them to very high levels, I just concentrate on the detail of the music. I am using a VTL 2.5 tube preamp and the match is great. The Aleph is a great amp, one of the best I have heard. If your room is small and you don't require your clothes to flap while listening the Aleph 3 would be fine, if you have the cash, go for the Aleph 5 or look into getting the BAT VK200 which is about same price in the used market. The BAt is also excellent. I also run this amp in another system and it has all of the qualities of the PASS, plus.
Good Luck buty with either you are on the right track

I used an Aleph 3 to drive my NHT 3.3's for a time. I was mostly interested in testing out the Aleph line of amps. The 3 is a great product, but it didn't have the headroom or bass control that I want. I've not heard the 5, but my recommendation would be to go for the extra power.

I have owned both the Pass 5 and the Pass 3 amplifiers. The 5 is a more refined sounding amplifier. It is not a power issue, but a design issue. The circuit and number of components internally is slightly different. IMO the 5 is well worth the extra $$. Also send a note to Nelson Pass via his website. His description of the differences between the two amplifiers is quite eye opening. The Pass 5 is a classic amp. Good luck.