My cables arrived a couple of days earlier than expected - thanks Witch Hat. For such a small company, the packaging is impressive, though thankfully not to the point where one objects to paying lots extra for the box.
My immediate reaction is that the Burndy between 52 and Supercap had the biggest impact, but the cable from SC to 250 power amp was also very effective. Together, they mean that Jaco Pastorius' bass guitar on Don Juan's Reckless Daughter is better defined/ controlled (and the deepest notes perhaps a bit louder?), and it is very noticeable that the placing of his bass in the stereo space is a lot less vague to my old ears. The harmonica on the Cowboy Junkies' Postcard Blues is also a great test (it should be hair-raising, not be comfortingly smooth, but it should also be listenable). By comparison with the my old Naim cables, that harmonica is cleaner and less uncomfortable at high volume, but no less compelling.
The cable from Superline to 52 fits into the same mould - no change to boogie factors or tonal balance, but a bit quieter where silence should be (if you see what I mean), a bit better at sudden vigour and with a little more control at both frequency extremes.
The jury is out on the source-interconnects from NDX2, CDS2. Initially, I think them a bit better than my old grey (i.e. same as lavender) cables. Comparison with a Hi-line is harder - I can hear that there is a bit of a difference - if pushed, I'd claim that the music seems to flow a bit better and that the bass on Bela Flack's Cosmic Hippos is more precise, but I am not sure that I am not imagining that to be the difference because of what the first 2 hours showed the effect of the first group of cables to be.
Some blind testing by ambushing friends will help pin things down, but that (and less tentative conclusions from me) will have to wait for a couple of weeks, given the above comments about burn-in time. I may yet end up preferring Hi-line to Morgana here (though that's not my guess as I type), whereas I'll be very surprised indeed if I prefer the Naim Burndy (say) after this.
As for why I hear what I do, I don't know of course, but I suspect that the screening issue may be key.
The back of my rack is a mess and that is really not surprising - 6 boxes need mains power, the 52 preamp has 6 cables in the back, I have 4 sources (inc tape) and the stack is only 2 boxes wide. I have moved boxes to keep (for example) 52 and Supercap a good way apart, and there is only so much one can do about the resultant pickle. The ridiculous but apparently necessary 'dressing' of cables generally and Burndies in particular is a particular complication, and one that one could not have imagined when a great hi-fi had 1 source and 2-3 other boxes (all of which just want to be a little distance apart).
Witch Hat cables are stiffer than many, and I am sure that they are not immune to really bad organising around what touches what. However, I strongly suspect that some of what I don't like as much about the all-Naim sound is my fault, and would be improved if only I could really make every cable hang free, untouched by any other or the floor or the wall. With Witch Hat, the last few hours of swapping cables and positions of boxes and all that seems to suggest that they are considerably less sensitive to mush (and worse) from cable-on-cable action.
Does this square with what other people hear?