Anyway, back on-topic. I may be getting a double-hit of benefit here, since clearly my speakers were not giving their best as I had them before (i.e. with the Tannoy-supplied feet sitting onto my carpeted floor).
I'm in the possibly unusual position of being someone who has spent a week or so listening to my speakers with the Gaias directly onto carpet, and then - just today - fitting the spiked feet (that go under the Gaias). I wasn't originally planning on using these - since I thought the Gaias would be enough - but I picked up a set in the Audio-T sale last weekend. I wasn't expecting much difference to the Gaias-on-carpet, but the difference has been surprising. It's mainly positive - I've gained a sense of air and articulation that I'd felt I was missing before - even with the Gaias - which I'd put down to the carpet, sofas and general construction of the room. Wrong. I don't know the physics, but clearly I'd been losing some HF energy due to how the speakers were 'floating' on the carpet. Now that they're decoupled from these spiked foot 'anchors', which in turn are coupled into the wooden floor (through the carpet and underlay) I have gained yet again. So much so I've had to dial back the +1.5dB energy to level, which I'd previously had to dial in to get a better HF:MID:LF balance. Now it is as it should be - pretty much bang on.
If there's a downside it's simply that now I have to recalibrate my ears to the sound. The 'liberated' HF detail and air, which very welcome, has also come at the expense of a slight reduction in perceived bass weight. Clearly my previous setup was not as optimal as I'd thought! Other than this slight reduction in bass weight - bear in mind I'm running with all bungs in place, which I can play with in due course - it's a huge upgrade. Everything is just as it should be - at least based upon the three albums I've listened to since fitting the feet.
My tale may not be representative of everyone, but it would explain why I was always just yearning for a soupçon more HF, or conversely why I had resorted to the bungs (maybe in an attempt to thin the lower end to bring it into balance). And, of course, maybe I now need to play a bit with listening seat position, speaker toe-in and suchlike - they may now be in the wrong place!
All this said, I think the improvements might well have been smaller if my room had a concrete floor or even was just uncarpeted.
Anyway, that's all for now - I'm a very happy bunny