I have the Krell 650M's matched with my Wilson Audio X-1's and I love it. I've audition the ML 33 vs the Krell 650M. The krell is very revealing and detail, excellent Mid and Thunderous Low something (in my opinion) the ML33's don't do as well as krell. You should audition both with your favorite recording. The opinion vary's depending on what Audio shop you audition at. It's very rare that you would be able to audition them both in the same shop. My suggestion is if possible get an in-home audition.
Levinson or Krell
I am currently putting a seperate listening room in my home and have listen to a wide variety of equipment. I have a pair of Wilson Watt Puppy 6's and I am currently shopping for amplification. I also own a Mark Levinson 38s pre and a Wadia 270 transport\Wadia 27ix dac. I have heard the Krell 350mcx's on the Wilsons and like the sound very much however I have heard lots of good things about Levinson 33H's paired with these speakers. I have yet to hear the Wilson/Levinson combo and I am open for suggestion.