Tubes tend to have a few disadvantages, apart from the inconvenience:
1 higher distortion, even though some like that.
2 load dependent frequency response. The best are borderline OK, but many have a terrible frequency response under realistic speaker loads. Just watch the graphs in Stereophile (and ignore the words).
3 low output power. Speakers need power, and lots of it, to move the mass of those cones. Without enough power, the sound will distort on louder signals, and be compressed. Again, some like this, but it is not a straight wire with gain.
Personally I am convinced that solid state amplifiers are a mature technology that reached sonic perfection in the 1980's. Hence, under controled conditions no differences between them can be detected. That is good news, because manufacturing technology by mainstream brands has made such amplifiers eminently affordable.
If you want to spend money on the amplifier with the best test results, look no further than the Benchmark AHB2. For some perverse pleasure in debunking audio myths:
http://www.homecinema-fr.com/forum/amplificateurs-de-puissance-haute-fidelite/mesures-ampli-yamaha-p...Litterature:
http://www.keith-snook.info/wireless-world-magazine/Wireless-World-1977/Audible%20amplifier%20distor...https://linearaudio.nl/sites/linearaudio.net/files/Valves%20versus%20Transistors%20DCD.pdf