IME how many watts you need mostly depends on your drummer and how loud he/she plays. But of course if the guitar is going through a tube amp that only sounds "good" loud then that's another factor. I played in a trio with a jazz drummer using a 60 watt combo and was plenty loud. Then I played with some other guys where my 200 watt rig felt underpowered, mostly due to the guitar, it would have been fine with the drums. But this is a discussion for the amp forum.
