what's the point?

though Julian H did say he would choose the Mark Levinson of all the amps he reviewed...(I forget which model it was)...

If a blind test has negative results it doesn’t mean anything. There are simply too many things that can go wrong. Besides, conclusions are reliable only after many tests have been performed, both for same system and tester as well as independent systems and testers. Repeatable and transferrable.

All my amps sound exactly alike with the volume off. 

There is no point in buying an expensive amp or an expensive anything for that matter. Buy what you can afford and components that take you to the experience you are looking for. Be reassured that amps etc. do make differences and nothing sounds the same. I have a good friend that debates this with me endlessly until we finally took the speakers out of his system and inserted them into mine. Of course my room is different, components etc. and so we tried our very slack A/B in the near field in both systems. Less than a minute, he couldn't believe it. Next my amp went to his system. Couple of minutes later he is trying to buy it from me. Not really a revelation. I do find the diminishing returns part of this interesting though. Of course how fat your wallet is the biggest factor but for me things start getting weird at about 10 k for amplification. I tend to look at the whole system and component synergy. This is where a crown amp suddenly for some inexplicable reason may work as strengths and weaknesses gel in your system. 

It's all for "fun factory" really. In the past year I've switched between a $1,500 Primare Class-D integrated, a Kenwood solid state integrated from the 70's, a $300 Kenwood power amp producing 150 wpc from the 80's, and a pair of $1,750 Cary Audio tube monoblocks. The difference between *all* of them has been extremely subtle. The tube monoblocks are definitely more different than the solid state stuff; kinda feels like I tweaked my EQ a bit. But the solid state differences were all very subtle "tip of the tong" sort of things. Not differences I would prioritize in any other hobby.

Get something that has enough power to drive your speakers to the highest listening levels you will achieve in your listening room. Get something that looks good, and is built to a quality level that makes you happy. And don't worry about how much it cost.