@evank Funny I bought a pair of Brimars from Upscale but they were noisy and they gave me all kinds of static about replacing them, so I went back to the JJ's. I think they give a more defined sound which I like, the Brimars sounded more muted to my ears. That is really interesting using the Gan Fet as the power stage on the Sphinx. Since I have one in the form of the MiniGan 5 I may try that one day, but I never thought the hypex units in the Sphinx were lacking. I love its overall sound!
The main speakers I see using with tubes are the two Lii audio full range, open baffles which both have efficiencies in the mid 90spl. Also the Klipsch RP-160s are rated at 96. These Lii speakers in the Caintuck inspired barrel shapes with no crossovers are magnificent, particularly for the money. I do supplement all my speakers in the main system with a trio of Syzygy subs to take care of the deep end.
The Rogue CM is a fine suggestion, if I wasn't focused so much on building my own I would definitely give them a listen. May do so anyway. Same for the Williston and other Chi-Fi. Thanks!
My own research has me looking at Dynakit ST-35,
And this Decware Zentriode kit, https://www.decware.com/newsite/SE84CDIY.htm
I did some parts pricing yesterday and the ST-35 would come in at $875 with tubes and the Decware Zen Triode would be a bout $500