I also still do and construct tube amps, for certain tasks. But I am not loving anything, for certain scenarios tube amps are still good, fully agree. Personally I still use them for headphone amplifiers only, as I utilize their inherited pair(second order) harmonic distortion as an asset to fight listening fatigue. I cannot mimic and create something like that using solid state, it is construction wise impossible to emulate that kind of thing, no matter how mosfets are close to the design even. Guitarists are the second area, but that's not the topic this time, there you have the task to achieve most wildly goofy and shitty sound as your main task, the more it distorts the better.
Solid state is a very very vast field. I like the less the better philosophy actually, but each classic design further evolved have their own strengths and flaws, there are not that many of them actually.... just like engines V8 or straight six. Multiple rail, dual current mirrors and most importantly how fast and deep the feedback is. Each of these designs do some sacrifices, it is intended to do so, it is electronics. In early days it was due of the poor element base, nowadays is vice versa what parts are the problem, the parts that were good are unobtainable and no replacement exist (small signal, high Rbe transistors for example, as renesas, KEC, Toshiba, National Semi is really dead in this area(say thanks to Texans, stock up LME49720/LM4562 if you like them, they will be killed)). We cannot expect anything more in certain things to improve the sound, lucky at least the only thing is better now are capacitors. Audio engineering is really a hard area, it is more hard than building PC electronics board as they allow deltas and forgive, have an error budget. Analog audio doesn't have that, it will start to "whistle" and blow out. The high currents, high frequency spectrum, part count makes it a dangerous path, and it is not loved by engineering tutors even and leave it out, people often misjudge it being a good start for learning, it is not like that actually. The other thing that comes close to it is SMPS, but they are really close... especially now with DSP desgins, just the music is always the same.
Same with old tube amps, after putting side by side the purity of 50ties and 60ties tubes versus the dirty Russians or China(I mean it the elemental tungsten purity this time). Well, it is whole different math, operating points.... and thus sound... I cannot manage to drive them equally and the result is worse, the datasheet doesn't work, the data is wrong. It is such an specific area, without experience it is hard to get an objective idea of this field, the problem is, with years the parts die out it is even more hard to grasp the reality. I would use guitar amp counterparts as some of them are decent still, and 6H3 is not of them here the thing was created for TV's not for audio even Russians themselves didn't put it in audio paths often, they did, but because of the soviet deficit and no parts available at all, they built things with all they had at hand, thus many of their designs seem irrational from engineering stand point, the reason was poverty actually, and now the poverty has turned out to be a fashion trend sometimes and reused. They had a shitpload of them in post nuclear vaults(storage hangars) to build up transmitters so they are still plenty of them as nearly all cities had them, then it was all stolen and they float up somewhere now.
My recommendation is to go cheap really. It won't matter really. 12AX7 (JJ Tesla) at the front... at the end I suggest something like single ended KT88(any they differ a lot even from the same maker), it will show you the boomy and fat tube character as this thing. Those are still popular, that's the main reason. And... pick up used, cheap paper cone speakers with crazy high sensitivity... and pair them with the amp and have a separate setup for tube... like vinyl corner.
Don't do receivers... those are like screwing with a rubber doll really. WhiteNoise should agree with that. They are made for comfort, lazy people wanting all in one place... in life it doesn't work like that, things consume space and power, you cannot build those things otherwise... unless you sacrifice something. For TV and Cinema it more than enough, music? Nope... I added this because of you idea to add something to the receiver as there is some sort of urge and unhappiness about the sound obviously and try to fix it.
