My experience with valves and amplifiers amounts to ownership of an Orange AD200B bass amp. it had eight KT88 valves in the main section and two 12AX7 in the pre, I believe. (If my memory serves me right).
I used the amp every Friday night for anything up to eight hours, as we practiced away in our three piece instrumental jazz/rock fusion sessions. The amp was partnered with an orange 4 × 10 bass cab and an Orange 1 × 15 bass cab at the bottom of the stack.
It was a fine sounding beast of a set up, however, after about one year or so, one or two of the KT88s gave up the ghost and I didn't know what biasing meant, or if I had to buy matched pairs.
In addition, if I'm honest, to my ears my Kustom Groove Bass 1200, a 1200 watt class AB solid state amp, sounded better than the Orange.
It was deeper, smoother, more powerful, more versatile in it's abilities to create different sound signatures, more reliable, cheaper to buy and easier to shift about.
It didn't look as impressive but I really loved that amp, it could run at 2 Ohms with 4 × 8 Ohm cabs connected although I usually ran two 8 Ohm cabs, so running at 4 Ohms nominal usually.
For me then, I wouldn't consider having valves in my Hi-Fi set up.
My current integrated amp is a Marantz Model 30. This runs two modified Hypex NC500 class D units in the main section, and to me it is a beautiful sounding piece of kit. I honestly couldn't imagine upgrading it because it is absolutely the best integrated amp I've yet heard when compared with other integrated amplifiers I've listened to.
My apologies for going off track somewhat.