A MC 500 is quite a unit, but its not a 462. A 452 should be smoother over the long haul and more revealing, but that would depend on the speakers. Austere speakers would reveal the sound right away. But speakers that are more neutral with out complex impedance curves the amps should be closer in comparison. I only heard the MC 500 once or twice seriously, and I preferred 501's. I even prefer 501's most 0f the time over 601's.
Everyone knows I love 1.2 K's and 1201's for testing speakers. Do they sound better than lower powered models, not always I would say, but they are a known commodity to me and if I hear something strange I know its not the amps.
I hate comparing things without a reference. It would be like listening to a Pair of M6's for the first time pushed with 611's/ C-52/ MCD 600. If I didn't like the sound I wouldn't know where to place the blame. And 95% of the time I don't like what I hear when auditioning something new. Its a terrible thing to admit, but that's me. If it sounds bad I am out of the room or turn the volume down in the first 30 seconds. Doesn't give you time to find faults. Apogee speakers were the first to do that to me with Threshold amps and pre-amp. The main problem was the Sony 101 CD player. I found out later. But even with different electronics and a more advance pioneer CD player, the Apogees were a lost cause as far as I was concerned. Every time I hear the current line of Mac speakers I have to get up and run to turn down the 10 K graphic control to 9:00 o'clock. -If the sound is still bad I keep looking . Most of the time its the recording but if thats not it its usually the tube pre-amp. I will say I love the C500T, however. But a 2300 and a 220 like MAC speakers run me right out of the room. I think the cause is higher freq. IM distortion, but its just a feeling on my part. I don't have access to test equipment any more to give me the answers.
Back in the 60's when everything was tube I never had the feeling I had to leave a room immediately . Even when SS came along I would hear something uncomfortable, but I didn't run. But when early digital came along I started running for either the exit or to turn the volume off. Wonder why. that is? Recording to closely miked do the same thing to me now. Be they analog or Digital. I know my hearing is changing and that overly emphasized highs above 4500 hz bother me, and especially above 6300 HZ. Something to ponder!