I have had my Offrandes for about 6 years now, so they are a slightly different version than the newest, and according to Bob he thinks the newer versions need more juice.
On my particular Offrandes however, my best found match so far is the Wyetech Labs Onyx monos. These things put out some very powerful 13 watts. I have tried multiple SS amps in my system and owned several PP high powered tube amps and the Onyx smokes them all, with bass in particular.
Another newer addition to my system that has really elevated things way up in refinement is the New Audio Frontiers Absolute preamp. Haven't had a chance to get it side by side with some of the big guns, but so far I haven't heard the others do some of the stuff that the Absolute is doing in my system. By big guns I mean stuff like the ARC Ref3, CJ Act2, Aesthetix Callisto Sig, and the Nagra PL-P.
So since you are looking for an integrated I would highly recommend the NAF 845SE integrated that was listed yesterday.
BTW, smart move to go up to the Offrandes, they are freaking great. I dread the day that my drivers wear out or something, but hopefully that is like 20 years from now. They are definately one of the best monitors made, and most definately "full range" for a monitor. I once had them measured professionally in my old room and they hit 35Hz at 0db, 32Hz at -3db, and 27Hz at -10db.