power amp watt range is for the Proac Response 2.5

If you look at the label on the back, ProAc specifies 25-200W.

I drove mine for years with 14W SET from Cary.

I had a pair of 2.5's. They're not difficult speakers to drive. The amps I used were, Pass Aleph 0s (40x2), VAC 30/30 (32x2), ARC VT 100 (100x2) and a Rowland 112 (150x2). They were all very good, but I think the VAC was the best one. I didn't have one at the time, but I suspect my Ayre V-5 would be a very good match as well.