Proac D48R

If you can stretch you budget a little ARC VSi75. In my experience, ProAcs love ARC tubes. The VSi75 should be enough to drive your speaks.

On the SS side Pass INT-60.

Both amps a little outside your budget but your speakers are worth it. What are you using now?

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?