Difference between amps

I'm with cakyol on this one all the way.. I have an older Adcom 7500, it shares a common PS. It works well for what it was intended 20 years ago.. It still works quite well as far as sound and easy to maintain. AB unit doubles watts to 4 ohm. Workhorse.. They used good parts too.

I have a Nord. Class d. It has 3 separate SMPS 1200A700 power supplies, one for each of NC500 amp module. Weird thing, a single 15 amp IEC fused AC plug.  Left me scratching my head. I'll tell you what. It is a sweet 3 channel amp, the BEST I've ever heard That's saying something.. Three separate amp with GREAT class A Sparco pro OA and Sparco regulators.
15 times lower output noise than IC regulators. They have 52dB (about 300X) better rejection of any noise coming into them, and 4X better load regulation than any other 3 terminal IC regulator.

I also have 3 pairs of their NC500 monoblocks.. (surround system). Very sweet when I use it. Pure analog surround, C45 with Class Ds. cool.
No fancy tool there..

Parasound.. I think is one of the best bang for the buck products out there. Hands down..

Mac. I've never owned a multi channel
I've owned Mac 50 years this spring. I love Mac.

Krell, I've owned monoblocks and stereos.  Powerful, and clinical. Paired with good speakers.. NO JUNK.. Good Electra Stats..small planars, Speakers that use Seas drivers.. good components. Krell like that,,

Nad is good. I don't own one. The neighbor does.. Very nice HT both the 2 and 5 channel Nads sound good. He uses a Krell 7.2 surround..That pre though it's older is a Heck of a stereo unit also..

Outlaw, never heard one

Emotiva, has its place.. I don't use them.. Adcom and Rotel are better SQ wise..

You had quite a cross section to choose from, too..

Regards

I enjoy my AHB2.

"...Only one spec matters: speaker sensitivity..."

I know you have posted this over and over but why limit yourself? Sure efficient loudspeakers make it easy to buy amplifiers, but that eliminates a lot of VERY good top end loudspeakers. I'm not willing to do that but I'm willing to buy an arc welder of an amp if I need to. .   

@redwoodaudio  Check out the impedance of your speakers.

https://www.stereophile.com/content/harbeth-monitor-302-40th-anniversary-edition-loudspeaker-measurements

If you averaged it over the entire spectrum it would be well over 8 ohms.  Sensitivity is not the only measurement that matters.

@twoleftears that's my point... easy to drive, yet sensitivity under 90 dB (87 per stereophile measurements as you linked).  limiting one's self to "highly efficient" speakers over 90 dB sensitivity, without regard for other factors, would be senseless except when using flea-watt amps.