I am using my Proac 1.5's with a Bryston 4b with good results. You might want to add the VT100 mkII to your list as I heard them paired to 2.5's; they sounded great.
Levinson vs Threshold vs Plinius vs Bry
Replacing my beloved CJ Premier 11A to power my Proac Response 2.5s with faster, deeper, tighter bass control (ie rythmic drive)without moving too far towards a dry, analytical sound. Considering the following used amps: Levinson 27.5, Threshold Stasis 200, Plinius 100, Bryston 4BST. I would really like to hear opinions of anyone with experience with these amps and especially if familiar with the Proacs. Thanks very much. Chet McHenry