I have a soft spot for good integrated amps, and, while the list is short compared to many audiophiles, I have enjoyed a few good ones over the years.
The list includes:
PASS Aleph (many years ago)
Bryston 4B (ditto)
Jeff Rowland Concentra I (loved it; >$5k, but I bought it used)
re-capped Accuphase e-303x (fabulous for a vintage amp)
HEGEL h190 (hard to fault)
Which leads to my answer to the OP’s question: the GATO AMP-150
This Danish-designed amp is largely under-the-radar in the U.S., but fairly well-known and received by audiophiles in Europe. The unusual aesthetics are somewhat polarizing – some love it, others, not so much. But I find the sound produced to be exceptionally good. It is very neutral/accurate, but with a touch of warmth, which I happen to like.
I used the GATO, HEGEL and Accuphase with my current Harbeth 30.1
The topology is interesting, and worth reading about (or watch the reviews below).
FWIW, but Steve Guttenberg and John Darko loved the amp, and have dedicated episodes to it. Darko compared it both directly and favorably to the more expensive Hegel H390.