A few things:
a) To the extent possible, avoid Chinese equipment. Yes, the prices are attractive as compared to US or Euro equipment of similar ilk, but the build-quality (and the tube quality) is pretty wretched. That is not to suggest that you might not get a 'good' one, but the operative word is "might".
b) There are any number of sources of very high quality present-production US-made-and-sourced tube equipment for those who do not wish to purchase used and do their own restorations. Some links follow:
http://www.tubes4hifi.com/bob.htm
https://www.dynakitparts.com/shop/st-35-kit-120-vac/
There are others, but I am linking you to Dyna-based products as they have been around since the 50s in one form or another and are very well supported in the after-market.
c) Understand that tubes are quite different in how they behave when "seeing" speakers. Those used to solid-state equipment understand that as speaker impedance drops, wattage into those speakers increases. So an amp that puts 60 watts into an 8-ohm speaker may put 100 - 120 watts into a 4-ohm speaker. Solid-state devices also tend to clip badly. Tube amps, or at least those with output transformers (very nearly all of them) provide the same wattage irrespective of impedance - within limits. And tube amps tend to clip softly.
In my office at this very minute, I am running an OEM Dynaco ST35 into AR Athena speakers. The room is 11 x 15, and it does quite well. That is a clean 17 wpc/rms provided by a pair of 6BQ5 tubes in PP. Output wattage is a function of tube type, transformer design, and internal configuration.
A bit on tube design: the 12AX/AU/AVX types are twin-triodes - that is two triode tubes in one envelope. A 7199 is a pentode/triode. 6SN7 is an octal dual-triode and so forth. Those Chinese tubes you are looking at are eyewash - a way to make a cheaper amplifier tube - as well as lock you into *that* tube from *that* source. Avoid them like the plague they are. Yes, that is an actual tube type actually produced for the US military - but the Military had a need for a compact special-purpose tube. You do not.
Look for a reliable tube amp from a local (US) source such that if you need help/advice/service, it would be available. Bob Latino at VTA is every bit of that. And Dynakit Parts is another.
Peter Wieck
Melrose Park, PA