Reading these comments .. A couple of things .. My first audio systems were tube driven - that's all there were then. If you wanted flat 20 to 20kHz frequency response (remembering that music frequency is is definitely not a constant) you need a high quality output transformer, an inductive device with capacitive elements (keeping in mind that reactance varies with frequency) to produce a flat frequency response. This resulted in the need for, for instance, non-symmetrically wrapped windings (there's an art to that - but maybe today's computers have taken much of the art out of that - I don't know). A good output transformer never came cheap. Then there's distortion where the degree of it is centered primarily around biasing, feedback, and individual device quality. Class A was always most desired but you couldn't expect it to remain linear and then get much power out (I won't get into push-pull, class B, class A/B approaches to getting more power out). Circuit design gets quite tricky. I did love the tube sound - but with the right speakers.
Ah yes .. Speakers. All speakers have their own distinctive sound. From my perspective, that's where you need to start and then build your system chain backwards from there. We all hear sounds differently and each of us have our own preference in music. To my ears, the best sounding speakers I ever heard were a pair of Apogee Scintilla all ribbon speakers. These were VERY low impedance speakers, each of which required large Krell or Threshold power amplifiers. You can love your tube sound, but no tube amp would ever do these justice .. and by the way, these were the only speakers I've ever heard that sounded so natural that, eyes closed, you'd swear the performers were standing right there in front of you. This was back in the 1980s and the cost was $7,000ish for the speakers. I figured I could somehow work that out. But then we had to start talking about the very expensive amps needed to drive them, and the size of room necessary for listening (being bi-directional they had to be far from the wall). Alas, the closest I could come to these that would fit my budget were Magnepan 4 ohm ribbon tweeter speakers. They also require a lot of current to drive them (Bryston 4B ST works well for these), they, when set properly provide a clean, detailed sound with great stage.
I guess the point is, it's all about the quality (to your ears) of the sound of the music that counts. And my experience says that quality runs linearly with cost (it's a long path before significant diminishing return starts to set in), at least that's the case if one's preference is music that features natural acoustic instruments (Jazz, classical, folk, etc).