Amplifier for ProAc response 2.5

what is the best matching for ProAc response 2.5 speakers? Integrated Amp. or Pre/Power Amp. anythings...
my brother-in-law's proac 2.5's sound great w/an alchemist kraken pre-amp/amp combo. he recently purchased another kraken amp so he can run either bridged or bi-amped - i can't wait to hear it!
I use VAC 160 Monos w/ Cat SL1 preamp. Great combination.
I almost bought the Proac 2.5 but after alot of auditioning I wanted a more full range speaker so I decided to go one step up to the 3.8's. I am driving them with VAC gear and I get outstanding sound. I am using the VAC standard preamp and the PA100 amp with Cardas Golden Cross cables. Just one terrific combo. I have had many systems for the past 10 years (Martin Logan,Dunlavy,InnerSound,Magnepan)and this is really the most satisfying. I now listen over 3 hours a day. Good Luck.