Proac D48R

I have had many pairs of Proacs since the early 90's.  They do love tube gear. I ran AR and Quicksilver much of the time. If you want something different, Primare is a GREAT match also.  For some reason, they have synergy.  Worth a listen if you are able to.  

I have heard the Sugden Masterclass IA-4 Integrated Amplifier with my Proac D-40r speakers (very similar to your D-48 speakers) and was very impressed with the results. It is in your price range new, with a minor discount, and is a real consideration if you are looking for an integrated amplifier. 33 wpc of pure class A listening pleasure.

that's interesting that you can get that speaker driving the way it can with only 33 watts.  I know it's only a measurement, however I ended up getting a larger Quick and AR amp as they just opened up big time with more current and higher power in general.  I have heard the D2 I believe it is, with a SET amp that was low watts and it was awesome.  The mids and highs just sang. I couldn't live with it as I need full sound, but there are some great amps out there now.

Does this mean that ProAcs and Solid State amplifier don't go well together?

Not at all milpai.....Pass as already mentioned and Plinius come to mind as does the Primare that Pete mentioned.  Some like Naim as well.  I used a Rega Elex-r with my Proac d20r with good success in a small room.  Keep us posted.  Regards.......