In general I'd say go for more power. It really depends upon your room size and expectations from the speakers, the kind of music you listen to and at what volume. I owned an Aleph 5 several years ago. I'd agree that it does have a softer, warmer, more tubey sound than most SS. I did find that I did not feel as if I were listening to a 50W SS amp in more ways than one...it just did not seem to put out much muscle an had a difficult time, even with 89 and 96 db speakers (at 8 ohms), in filling up a larger room with sound. In a smaller room it was great, though you can fry an egg on one when it is warmed up and your electric bill is sure to go up if you choose to leave it on 24/7 as is optimal. Never heard an Audiolab so cannot compare. I do like the Aleph 5, but to me it performed like what I might expect from a 20W amp rather than a 50W amp. I've read many folks say that the Aleph 3/30 is a better bet, but you'll have to search the archives for more input there.
Marco
Marco