I've heard ATC speakers, though not a user. I've also seen some ATC models with very low sensitivity. This simply means that they need more powerful amps to produce the same volume level as a more sensitive speaker.

If ATC is recommending a minimum of 50 watts, that suggests to me that they are low in sensitivity. Many speakers recommend minimums of 15 watts, for example.

Your room is small (so is mine) and you would be listening in the nearfield and would probably be OK around the 50 watt minimum if you don't like to rock the joint. Whether you go with an integrated or pre/amp combination is not really a big deal provided the pre and amp mate well and allow you to drive the amp at full power. At budget levels, I would probably opt for an integrated. You can usually get more bang for your buck when the manufacturer can cut the cost of another chasis and design the integrated with better quality parts instead.

I saw your previous entry and thought all the amps you were considering would be up to the task. Even the Primaluna at 35 watts would probably work if you don't like your music loud. The benefit of low sensitivity speakers in a nearfield listening situation is reduced audible speaker hiss. At low to moderate volumes, the Primaluna would probably mate fine and any inherent noise from the amp would likely be benign with low sensitivity speakers.

I guess the questions would be, how loud do you like to listen and just how sensitive are the ATC models you are considering...along with are they 4 or 8 ohm speakers?

If you can post the actual speaker specs, we could probably offer a bit more advice.