Then we can build line stage first, with amplification about tube mu, or 17. We can use it for (pre)amplification of low-signal sources (hundreds of mV) to "drive" power amplifier.
But, our linestage can be a good "driver" for SE tube amp with CD player input - 2Vrms, say for EL34 in triode, or even 2A3/6B4G.
Once "armed" with experience building line stage, additional work for SE output stage would be trivial :-).

The amps wpuld be next the next obvious progression. However, instead of using the 2A3 is there another, less well known, power tube we could use? I don't know, just something to be different......Colin

Well, I didn`t try them all, of course. The last 5 years I listen to the music through my DIY monoblocks (PPP, 4xEL34 or 5881 sometimes, concertina phase splitter, Plitron/Amplimo toroidal OPTs, triode or UL, no NFB loop). I`m satisfied, only criticism can be low damping factor - little "boomines" through rear ported speakers, JBL4208.
As you can see, I`m not an audiophile, I even listen "lo-fi" recorded music...
I have "neverending" breadboarded 300B amp, tube rectification (CLC + LC for the driver), I constantly (but slowly) try different things. Right now it has a cascode 5687 driver...maybe I`d solder this mess together in the 2HE rack case one day... Two toroidal PTs, 2 Lundahl 3k OPTs, 4 chokes, Svetlana 300B tubes.
Well, to answer your question directly - for the good, but simple enough amp I`ll vote for PP, good quality OPT, say "Plitron" 6k:5Ohms. Individual bias pots for the each output tube (say EL34, 6550, KT66, etc.). Split load (concertina) phase splitter with E182CC, ECC99 or 5687 tube. Power supply with another "Plitron" toroid, SS rectification, CLC+ LC for the driver(say, Lundahl chokes),B+ about 390V, good quality passive parts. About 25W in UL or half of that in triode. No NFB loop, AC heaters (good enough, IME). As you can see, 90% from the Vanderveen`s book, but it works well. (Hehe, Pltiron/Amplimo even has a similar kit - no affiliation:-)).
That`s very subjective and YMMV, etc. To be continued...

Merry Christmas to everyone!

• VDV3070 amp

I'm thinking that when we get around to doing a power amp project, it might be nice to have it be something like a parafeed SE amp. Not too complicated to build, good for a beginning DIY'er and nice sounding. Maybe a parafeed 300B?