Tubes can be really good, but the differences between them can be very subtle, if audible, at all. Outut tubes can easily blot out the benefits of preamp tubes and they do vary in sound. One thing to be careful about- when the verbal description of the sound of one amp or another becomes filled with strange adjectives, it's time to run away.
Watch this video- it's about 12AX7 tubes for guitar amps, but he makes some good points about how different they can be, or not.
Then, the point that an amp or preamp has more than one tube in the signal path, so the differences can be clouded by that.
I'm not trying to say that I don't like tubes- I do, for some uses. I have owned several guitar amps with tubes and a couple that are solid state- for that, I only use tubess but the solid state stereo amplifiers I have owned sound better than the tube stereo amplifiers, the sound of which degraded over time as the tubes aged and the current to them affected them differently and that's another point to consider- do you want to be required to have the equipment serviced periodically, or do you want to use it? I worked at a music store more than 50 years ago and started working for a stereo store in Feb, 1978- we had someone who would come into the music store to pick up equipment to be serviced- I Iearned a lot from him and at the other places I worked for all had service departments, some with people who had worked with tube equipment for a long time. I learned from all, but the one thing that overrides my enthusiasm for tube equipment is the knowledge that it will need service sooner than most solid state equipment.
The look, smell and often warm sound from tubes is great, but at this point, finding a good service tech is becoming difficult. In some places, it's incredibly difficult- nobody wants to pay for shipping if something isn't repairable at the store and needs to be sent somewhere else. If it was designed and built outside of your country, it might be a bumpy ride. I have worked continuously in audio and AV/Home Theater for more than 50 years- used to be that we had many repair shops, then they dropped out one by one. Last Fall, the shop that did service work for almost all stereo stores and who was authorized to repairs for most brands in the SE part of Wisconsin closed. Now, everyone is either not taking equipment in for service, scrambling and hoping a new guy can do it or finding out they made a mistake by trusting someone who couldn't deliver on their promises.
Call around to find a good service tech- I don't know where you live, but maybe some stores can recommend someone.
People have aged out of the service end of the business and manay have passed on- those of us who have been in the business for decades are saddened by the fact that this job is no longer a decent path as a career.