Does a turntable mat make any difference?

Yes, they do and you can forget about any specific recommendation from this thread unless they have your turntable, maybe arm combination.  There are simply too many variables.

Anybody try the somewhat newish turn table mat from Synergistic Research? They’ve also developed a record weight that seems somewhat confusing. They must be the best because they cost way more than any other record mat/weight on the market.

IIRC, I measured 50 ohms impedance on my SLs at 100 Hz. But don’t hold me to that until I get home from from Vieques (a small island near Puerto Rico) and consult my data. (It might have been 50 ohms at 50 Hz.)

Mijo, you write, “I cannot believe this (inserting the Bricasti at 5kHz) won’t be an improvement.” Thus I guarantee you will perceive it as an improvement. I personally don’t agree with forcing a speaker to create a flat in-room response regardless of driver limitations, especially in service to a processor, but you already know that. I think when your brilliance control got hot, the speaker was telling you to lay off. Anyway, I’d love to hear the results. Also, when S’phile analyzed a full range SL speaker (forgot what amp and which model SL), it measured very flat out to 20kHz, without high frequency augmentation. Maybe that was at a SPL well below what you like.

I've got a techniques 1500c if that helps