You certainly can't go wrong with the all Mac system. I am sure it will sound amazing. Mac and SF go hand in hand and have amazing synergy. The amps are incredible, you have the best of both worlds, SS to low end and sweet tube sound for the mid and tweeter. It will be hard to beat this set up. Although I disagree with your assessment that Aidas would be too large for your room. I've heard them in much smaller rooms and they sound mesmerizing. You can always upgrade in the future if you decide to go that route. Remember, speaker is the most important component of your system and you should maximize your spending here. Also, don't let anyone degrade Mcintosh, they're beautifully made and bulletproof. Of course, they do come with their own house sound, which is why they polarize people so much. It's a very rich warm and detailed sound. Slightly colored ? Definitely. But who cares, they sound wonderful. SF used to have a reputation for sounding too warm, but modern day SF are a different animal.
I also use Mac gear for my SF set up. I have SF Elipsa SE with MC452 and C2600, along with turntable and streamer. Sound is very pleasing, warm and detailed.
Mac tubes don't really sound much like tubes. So 901 will sound very close to Mac SS amp. I could hardly tell a difference between Mac SS and tubes. I wouldn't say you're gonna limit your speakers, 901 are fantastic, but you should also try a full tube amp at some point.
However, if you ever want to hear what your speakers are really capable of, you should try a SET tube amp. SET (single ended triode) is the most pure form of class A amplification. Tube amps have different configurations, as you will read and learn, (pull-pull, pentode, ultralinear etc).
SET will give you the most tube like sound possible. However, it is very very expensive if you need a powerful amp. I also have an Italian Mastersound 845 tube amp, which uses 845 tubes in SET. For your speakers you will need massive power, most likely Mastersound Pf100 mono blocks in SET (120W/ch). They are about 50k plus you'll need a preamp, another 10-15k. Once you hear this, you will not want to listen to anything else. For now, you should enjoy your new rig. You may never want anything better after this. It all depends how infected you get with the audiophile bug.
