In reply to:
You could pump up the mid-bass for warmth and cut the sibilant frequency which is below what the usual treble tone control covers.
Sibilance does not come from high treble.
Anyone can make a regular S sound sibilant just by holding the letter sssssso that everything sssssounds sssssharper with sss notessss.
I've done the M40 vs M60 test for sibilance with mdrew's original recordings that he had complained/asked about. I'm going to do a listening test with my big Tannoys and the M60s later today. In a preliminary test with the Tannoys, the sibilance from mdrew's recordings is still present. The recordings definitely have alot of "s" sounds. However, the remaining question is, do the Axioms enhance this more with their forward sound?