I bought a Latino VTA ST-70 amp to dabble with tubes. I wanted to see what all the fuss was about. That $1400 tube amp beat the britches off a much much higher cost SS amp that was well known w/good reviews. That 35wpc stayed in my system for 10-12 yrs. Then I got a Don Sachs Kootenay 120 @ 65wpc. It is based off Bob Latino's ST-120 but with all upgraded parts including 2 discreet power supplies. I bought it because Like you, I really liked my ST-70 sound. But I figured the upgraded parts would make a good difference in the quality of that sound. It did.
But I had a very good preamp also prior to getting a new amp. You haven't listed yours. This is a good reason to list your system on the systems page because it helps others to analyze your issues. That said, I've had amps from 35wpc to 800+wpc. The 35 wpc & 60wpc tubed sound best. In SS, a 45wpc shamed to other SS.High wattage is needed for PA's which you need to cover a parking lot or similar. Unless you have a difficult load, 60wpc is usually plenty enough to drive most speakers. Merry Christmas