best tube amp 1k new or used?

Used, the VTL ST-85 will often be available in this price range. That would be one very worthwhile option. I'm sure others will have additional suggestions.

Quicksilver KT88 monos.

Googled for "SAK2 speakers" and didn't find anything. Neither did "Audio System SAK2" turn up anything useful.

What kind of speakers are they?

I'm sure he means "System Audio SA2K"

Does anyone know if the SA2K is tube friendly? From what I gather, the speaker is 86 db efficient and 4 ohm nominal load, so not particularly tube friendly, although there are speakers with similar specs which are tube friendly, but not many of them.

It would be useful to know what you're hoping to get out of a tube amplifier versus what you're driving them with today. The sonic signature of tube amplifiers is as varied as the colors of the rainbow -- there's not *one* tube sound, although at this price with those kinds of speakers, I think you're locked out of SET or OTL amplifiers.

Having said that, why the Brio R? It's an integrated, so are you looking for an integrated or a power amplifier? What does your system look like today?

The VTL ST-85 does seem like it fits the requirements, unless of course you're looking for an integrated rather than a power amplifier.