Amp for ProAc Studio 2 speakers?

I've just acquired a pair of old ProAc Studio 2 speakers, what Amp/Amp-Preamp would you recommend to get the most out of these speakers? I was told the mid and high range are fine but the low needs some filling in if not driven hard (was planning on getting a sub to fix that). Would like to keep the budget under £800. Your help would be much appreciated.

As a long time Proac user, Tubes rule! Proacs sound best with tube amps. Manley amps sound particularly amazing and are my personal favorites. You can't go wrong with them.