I've just been reading through this thread and it's refreshing to read of others positive experiences with the Harbeths SHL-5's.
I've been a owner of these speakers for around 4 years now, and have found myself, like the thread starter, tired of changing gear needlessly and after 40 years involvement in this hobby, that's been a LOT of gear.
These are the most satisfying speakers I have ever owned, even though I run them in a apartment room that is really too small for them and according to some shouldn't work [It can be done

, in reply to somebody previously asking if they would work in a NY apartment]
It depends on your floor construction mainly, and if it is carpeted or not.
This will determine what type of speaker stand to use.
I'll give details if asked, based my reasoning for them and results after trying a lot of configurations.
As for Amps to use with SHL-5's, well it has to be SS amps if only for one major reason.
The higher damping factor found in SS amps is needed to control the bass, which can easily turn into a boom with a lossy cabinet bass reflex design like this.
RE the question put: What does Alan Shaw use Amp wise.
He uses a pair of mono amps for the UK manufacturer LFD as his reference .... he let it slip a few years back when somebody asked at the Harbeth forum why he didn't put Bi-Wire terminals to allow Bi-Amping on most of his speakers..... his answer went along the lines of if you run Bi-wire you need both amps to be meticulously calibrated to each other [he has his calibrated every few months], and it was far more likely that the amps would drift from ideal before any drift between the speakers crossovers components, thereby defeating any gains that your average audiophile would get, since they most likely wouldn't get their amps calibrated.
As for the collection of other amps he mentioned....I'm pretty sure they would be old Sudgen amps....which have been going since the mid 60's in the UK virtually unchanged and are pretty much bullet proof, plenty of them around.
Around 35w heavily biased into class A.
Not unstrangely like the Alph 30 that seems to have been found to work well with the SHL-5's