How to proceed?

@jtcf 

Thanks for your comments about the Jay"s. I hope you are right, as I wouldn't know which other transport to buy, at a similar price point!

I live in the boonies in an area of large parcels, each with its own transformer. A PS Audio regenerator had no discerniblle sonic impact  when demo'd 15 years ago but I may, nevertheless, try again with a different unit.  

@audioman58 

Thanks for your suggestion.

I'm familiar with a the positive regard for the T+A.

I'm not sure it's the best choice for me.

@stuartk This thread has really gotten going! Sibilance is such a multi-caused problem, that if I were you, I'd try a process of elimination approach that causes the least disruption. @alexatpos is on to something very important with (a) positioning. If you're in a constrained space, do what you can to ensure that you cannot fix the problem with positioning before (b) trying cables to change the problem. If that doesn't work, (c) an equalizer would be a very effective and flexible tool but if that's not possible, then (d) seeking a warmer power source (at least as an experiment) would be the ticket.

I had fairly bright standmounts and a solid state A/B amp (a fairly robust Atoll IN200 SE)  was too bright. I brought in a Pass XA-25 and while it didn't cure my problem -- because I had Beryllium tweeters -- it helped a lot. A Class A amp is an easy way experiment, not least because if it works, you could sell your Hegel and probably not lose much money. 

@hilde45 

Thanks for your suggestions, Dave

As you know @decooney is working with me to solve this puzzle. 

We are going through process of elimination. I've moved speakers around some, so far, without impacting sibilance but I can't say I've done enough in this regard. 

When @decooney comes up, he can assess this, among other factors. 

BTW, my stand mounts have soft-domes and are not bright     ;o)