I do not know your Harbeths, but become increasingly convinced there is so much to improve upon in front of any transducer in the way of not only equipment, but power conditioning and cabling. My transducers (3 years now) continue to improve markedly as power cables and interconnects break in.
I've invested considerably in equipment stand, floor stander platforms, wall outlet and of course room treatment. I believe many of us go down the rabbit hole chasing ghosts. Those Harbeths being quite good may well have not reached full potential with what's in front of them. Or, I could be wrong. Cheers