Krell FPB vs Plinius SA-103 vs Pass Labs XA60.5

Chuck, many thanks for your input.
I really do not think the congestion is due to the amp. running out of steam. The FPB300c is rated at 300 watts steady state but is likely to be a lot more when playing music. And as you said, the VR-33s are 90dB sensitive and while I listen quite loudly, its not at excessive levels - room size is (28 x 23) ft.
I have heard some audiphiles remark that this tendency to congestion with complex music is a trait of Krell amps? Also, Krell does have the reputation for a bright edge to its sound. Having moved onto the FPB300c from a KSA150, I would say the FPB is vastly better in these respects. And I should put into perspective that my comments is really nit picking as I've been very happy with the system until the FPB300c went pop.
One other point, my inclusion of the FPB400cx is probably a case of playing safe as the FPB300c was so good. I suspect the Plinius and Pass options is probably overall better than the FPB400cx (?) though I do not know how they will gel with the VR-33s.
Grateful for your comments & advise. Many thanks.

Thanks guys for all the comments & advise.
Chuck, I will look into the Spectron, which I think is a class D amp? I have to say my first audition of a class D amp (a Linn) was not so favourable; the sound was clean & clear but a bit sterile. But then the Spectron may be different.
Thinking about it, Unsound's idea that the congestion may be in the recording is probably correct, as not all CDs had this problem. It’s a nice surprise in a way to see so much support for the Krell option; after all I really enjoyed my time (almost 8 years) with the FPB300c; it’s a safe known option and the 400cx should better the 300c.
Knghifi, my signal cables are Pure Note Vanguard from player to pre-amp; Pure Note Alluvion balanced from pre to power amp, and VH Audio Chela speaker cables. Power cords are a Virtual Dynamics Master from the wall to a Hydra 8 conditioner. Then a Lessloss DFPC to the Modwright player; a Black Sand Silver Reference Mk V to the Modwright power supply and another one supplying the Calypso pre-amp; and a separate Virtual Dynamics Master from the wall to a separate Hydra 2 conditioner used solely for the FPB300c. None of these cables are to my knowledge bright or thin. I also extensively use Herbies supports for all components and speakers.
As for tubes, I am using Sylvania 6SN7 GTB valves in the Modwright 5400ES, and a Create Audio 5AR4 rectifier tube in the power supply.
At this point, I really should emphasize that the issues I raised re congestion and brightness are very minor and in the main are only from certain CDs. As Unsound said, more than not, its an issue with the recording rather than the system that we are talking about here. Remember prior to the FPB300c going up in smoke, I was very happy with the system and had no intention nor inclination to upgrade. Its just that I am forced into replacing the 300c as it was just not the same after repairs.
It will be great to get some advise from Plinius and Pass Labs users though before I decide; any of you guys out there? Especially those who might have done comparisons with the other and also Krell FPB power amps? Many thanks.