I’m glad this topic finally came up!
But seriously, I’d have to say that while high-quality equipment can definitely improve sound quality, I’ve found that room acoustics have an even greater impact. This includes differences between tube vs. solid state. Don’t get me wrong, good equipment design is still important, but acoustics can significantly influence how you experience sound. In fact, I recently added additional diffusion in my listening room, and after adjusting them properly, the difference in sound quality has exceeded most other gear improvements. There is real power of optimizing room acoustics – it can surpass the benefits of many equipment upgrades.
Once a room is fairly well dialed in, though, at *that* point you have a truly level playing field and any additional changes to gear can be evaluated with more objectivity and confidence.
A key question to you, OP, is whether you have the room as tuned in as it could be? If not, that is the next lever to press.