Diversity of opinion over what

It's a matter of taste. Benchmark DAC1 in my system sounds very natural and transparent but to many it sounds sterile and analytical. Adding distortion or noise would likely make it sound more vivid same way distorted guitar appears more dynamic then clean sounding guitar. I don't have John Atkinson's experience either but have to admit that Benchmark surprised me with its sound purity making impression of less instruments playing together. Today it sounds absolutely normal to me. As long as we are not talking about bright or unpleasant sound it is better to spend more time getting used to new gear to avoid hasty decisions, especially when it needs long break-in time like my Rowland 102 amp, that sounded best after about 400 hrs.

different speaker loads bring out different sound qualities in amplifiers as well

also, tonal balance is a fickle thing and speaker placement and cables etc can change tonal balance in a flash

maybe the persons expectations play into it as well and after time he may change his mind...?

Everyone has different needs and expectations nad likes.
There IS no such thing as reproduced absolute sound.
Naturally some folks will disagree.
I have preferences, so does everyone.
We each find equipment which fufills our needs.
Not someone elses.

It's not just that different folks have different tastes, it's about synergy too. I'm not trying to offend the OP, but I have always found JM Lab speakers to be hard or analytical. I'm sure they would sound their best with some warmer electronics. Speakers that I enjoy, Verity Audio Parsifal Ovations, others have called lifeless or polite. They will be if you put warm electronics in front of them.

It's about balance and synergy. Warm electronics + revealing speakers = good. Revealing electronics + revealing speakers = not so good, and vice versa. Oh yeah, don't forget to through cables into that mix too. I've heard enough different sounding pieces of gear that I think I can take just about any unit and place it with the right accompanying gear, make it sound very good, or make it sound very bad.

Most of us arrive at a similar location via very different paths. Synergy.

Yes, I think that Jmcgrogan2 nailed it. I personally do not use the word synergy (it's a bad word in my vocubulary) but use 'impedance matching' instead but the undelying principal is the same. Electrically the amplifier must be able to drive the speaker it's being connected. And, if the speaker is too capacitative (for example) then the amp must be stable & not break out into oscillations (which is often manifested as harsh/brittle sound), if the speaker is a low impedance load in the bass area then the amp must have sufficient current delivery.
Like Jmcgrogan2 wrote the speaker cables & pre-power cables also make some difference in the sonics.
It's entirely possible that the amp-speaker interface was just fine your case but it could have been the cables or some electronics upstream? Debugging this is a hard & time consuming job but if you do go down the debugging path you end up learning a lot about what makes your rig tick & that is always worth the effort. The easiest thing to do is to dump the amp....
Anyway, the amp-speaker interface has to be considered very seriously esp. for 99% of the speakers in the market that continue to be ill-designed.