I have used Pass and Sugden, Pass are just wonderful sounding amps, not integrated of course. The Aleph series are quite cheap now, if ugly brutes(Borg cubes). Just pick your output, the 3 at 30watts, going up to 100watts maximum. To state the obvious, more power gives you more flexibilty. Sugden are similarly warm but detailed, just a great fit and forget choice. If you want an integrated, the 21 is a good choice, but only about 25watts, maybe not enough. The more powerful masterclass series will give you a great result.
On a general point, some companies go on making quality good value products year in and year out, Pass and Sugden are 2 examples. I can't think of a bad product either of them have ever produced.
On another general point, I think it is always good to have a bit more power than you need. I bought a Lavardin IT(another great SS integrated by the way), to match my Living Voice Avatars, which they did, now I have changed to slightly less sensitive Acoustic Zen Adagios, still a great match, but I think I need a bit more power