my shortlist for integrated Harbethsuper hl5 plus xd - please advise

You should check out LFD ( solid state ). Give GR a call as he is a big Harbeth dealer! BTW, I own those speakers and I use tube amplification!

https://generubinaudio.com/shop/ols/categories/amplifiers

Moonriver 404 or 404 Reference, I was told they were being developed using BBC family of speakers all though not exclusively so, are said to sound great with Graham Audio speakers.

I would also seek out a VTL IT-85. A magical amp with many Harbeth. At 70 wpc It has the power that an HL5 needs. Also as important it has a more neutral (for tubes) tonality which the Harbeth's also need.

i have said this in other posts about harbeths but i will repeat here for the benefit of the op’s

there is no right or wrong answer, we all hear differently and have different preferences

that said, i have owned many harbeths (mon 40, c7, shl5) and i believe that to give them the best possible full range, top to bottom response, they benefit from a pure solid state amp with strong damping factor/woofer grip

the nature of the harbeths is they do their magical voice thing (as a function of their driver material and resonant thin wall cabinet) but they lose resolution up top and slam and tunefulness down low without the best that strong solid state amplification can provide

you CAN make harbeths sound great down low with rel (or other good subs) but to my ear the harbeths sound a little too smoothed over up top with most tube amps

i do concur with @yogiboy that lfd's can work well with harbeths sonically, as those amps sound fast, pure, with good control down low, if you can live with their barebones nature functionally

@gryphongryph I am not sure if it came from Gene Rubin, but that's definitely a sign, that he carries both Moonriver and Harbeth