My 6922 Tubes Are Too Bright!

@ 25105 regarding Voskhod 6n23p tubes. As to their sound in the BHK250 - warm in the sense that the mid range seems to have slightly greater emphasis, lots of "air" around instruments, treble is detailed but definitely not etched, bass isn't fat or bloated. They allow a more relaxed perspective as if you moved back a couple rows in the audience. I've got several sets of 70's and early 80's Voskhods I accumulated in my many years of collecting gear and tubes. FWIW, I did order a couple more sets from an Ebay seller in the Ukraine because the desirable vintages aren't commonly found here in the USA.  I've not received them yet so I can't say what I think of the seller. 
https://www.ebay.com/usr/tubesandsound?_trksid=p2047675.l2559

Go to Upscale Audio website. Good coverage, user reviews, some vids and descriptions of 6922s and variants. Kevin Deal knows tubes. There is a certain synergy with tubes in each individual system. Especially when various components use them.

Another recommendation for Telefunken E88CC / 6922. They are not cheap but worth every penny.

When I retuned my VT100 MKII, Audio Research gave me the option of using JAN Phillips 6922 tubes (actually, 6DJ8 tubes) and they provided much more extended bass and smoother highs.  That said, I do not know that they would be an improvement on the Amperex tubes as regards the highs.