You have ( or had ) a Krell FBP300c that put out 300 wpc @ 8 ohms. You say that it got congested on complex passages. The VR-33s are rated at 90DB sensitivity. If it was because it ran out of headroom, you need to know that.
The XA60.5 amps put out 60 wpc and the SA-103 puts out 125 wpc. If the FBP300c wasn't enough, will these be enough?
If it would work, I would try the Plinius first. It's reputation is sparkling, although it's not pushed like the Pass and Krell amps. I'd have one but I'm in a small room and can't take the heat.
My old XA30.5 had me sweating and was congested in complex passages from running out of steam. My KSA-50S was in a larger room, so I didn't notice the heat and I really didn't notice it being congested although it certainly wasn't the amp that the FBP300c is.