As already mentioned, placement of Kans is king! I mean more than I say however, because not only do I mean close to the wall, I mean close to the wall on Kan stands on Mana sound bases, with glass, with an appropriate interface between the glass and the stand spikes. Let me expand...
My mk1 Kans have been on mk2 Kan stands on top of two pairs of small Mana sound bases (with the aid of an improvised piece of MDF) for a while now, but I recently got some glass made up, ala Mana glass, so I could put the kan stands on glass. Although it tightened everything up and made some aspects sound simply superb, it introduced some very bad stuff as well. Having spikes on both sides of the glass created a sort of harmonic resonance so that certain high pitched frequencies became unbearable, perhaps like having too much feedback from an electric guitar. I was reliably informed having spikes on both sides of the glass doesn't work so I'd need to add an alternative interface between the glass and stand spikes.
The first interface I tried placing between the top of the glass and the stand spikes was bits of silicone and although it solved the wonky harmonic issue, it seemed to slow the Kans down and even muddy the overall sound. I then tried some rubber pads intended to be used as feet on an LP12 and it was more or less the same as with the silicone. Finally, I tried placing some small pieces of plastic (I think that's what it is) between glass and spikes and voila, my Kans are now out-of-this-world amazing. I actually used used 8 pieces of plastic screw covers, the kind of thing used to cover screws in flat-pack furniture, and I now have a system that blows my mind (and ears!)! If I had to put a value on these bits of plastic, I'd say £1k+. Admittedly, I had to have the Mana bases, glass and Kan stands for them to be of value, but seeing as I already do, they're by far the best unorthodox upgrade I've ever done. I guess these bits of plastic are the keystone to my archway of audio nirvana
I now conclude that my system lacks nothing (obviously it's bass-lite, but that's par for the course with Kans) and any future changes I make (such as buying a Teddy Pardo amp in the very near future) I'll do so because I want more, not because I think there's something wrong with it as it is. If anyone is in doubt as to the amazingness of Kans, come and visit me (in Glasgow) for a sonic treat - I might even make you a nice coffee as well