With a lot of speakers it is not so much the raw power available, like for example 200wts at 8 ohms, as it is the current delivery to speakers with lower impedences i.e. 4 ohms and below. Amps which double power output at 8 ohms when it droops to 4 ohms or lower, are a good candidate for success. Those which do not may well have difficulty driving your Proac's I suspect (I've never seen the actual impedence curve of your speakers).
Re raw power - 50wt amps which double from 8 to 4 ohms will sound more powerful than their actual wattage suggests especially if your speakers have an efficiency of 90+db. If you don't listen to them excessively loud in a medium size room you could probably drive speakers with a 86db efficiency. I've used an loved high current 50wt amps with 86 db speakers with difficult impedence curves in a medium size room.
FWIW, I've never had Proac's in my home.
Re raw power - 50wt amps which double from 8 to 4 ohms will sound more powerful than their actual wattage suggests especially if your speakers have an efficiency of 90+db. If you don't listen to them excessively loud in a medium size room you could probably drive speakers with a 86db efficiency. I've used an loved high current 50wt amps with 86 db speakers with difficult impedence curves in a medium size room.
FWIW, I've never had Proac's in my home.