krell KSA 200S or 100S to drive mani 2's?

I haven't had any of those Krells. I do have totem Mani 2's, have used them with a C-J MF2500A for quite awhile, & am very very happy with the sound. Oh yeah, I have a "Tube pre on top" as Chazz suggested.

What amp are you using now, & how big is your room?

I have a KSA 300 and the great thing about the KSA is should you get an impedance swing (I sold latter Krell FPB series fro '96-2001) some speakers that have stated specs like our nest seller B&W 803 was 90db @ 8ohm but that could go down below three ohms.In any case KSA series was only amp series that Krell made that could go stable into 1 ohm load continuous (which with mine makes it 2,400 into 1 ohm!) and some say it actually goes stable into .5.So you might be able to get by with 100 watts but like they say you can't have to much.

With Krell you get the (IMHO) good and bad with clean high end and nothing with more grip on bass though I think both A and A/B Krell has slightly metallic or "etched" mids-then again I like tubes a lot.But it's a totally different sound with AR and I am sure you know the difference.Tube pre on top of Krell would be great with Mani's (which are classic great speaker).Haven't heard the AR but it has a great rep as one of their best amps. like.Other high current stuff would be value wise Bryston ST series 4 and up.You don't need a pair or Parasound JC1 400 wpc mono's for them (I love that amp-also like the Plnius a friend wants one for his Forrest's).Long story short Krell will give you the grunt you need at 200 wpc but 100 if not in to big a room or too loud would do it.
Chazz

The KSA-200S would be my choice. But I could live with the KSA 100 or Audio Research in the short term. I say this from experience and based on the type of music I prefer (Jazz/Electronic with some vocals sprinkled in) which is very fast and dynamic.

Great monitors IMO sound better with amps that provide ample current capacity and increased headroom. The result is both more musical and more satisfying in the longer term.

My previous monitors (Wharfedale Diamond, Monitor Audio, Dali, Vienna Acoustics and Totem) were paired with different tube and solid state amps all with higher current or Class-A output.

Your sound will be more relaxed and confident. Complex passages in songs midrange and bass will have more dynamics and better soundstage.