Those are indeed very good tubes.
I designed a SET in order to win a wager, just 15 watts for efficient speakers, when I get some free time it will become a headphone amp as well. The power tubes are not something most folks would have heard of, they were used in Russian and German transmitters in WW 2. The research and getting pentodes to work as triodes was part of the fun.
I own some decent solid state amps but only use one as part of a 7.2 system, other wise it is just Class A tube amps for me. They take me back to my early days in audio and I hope to keep that alive for my son since he will inherit the majority of my gear.
My son got me into Schiit gear so both of us own plenty of that. I especially like the DAC's and the Freya +. There are a couple new products by Schiit that pique my interest and one most certainly involves tubes.