No effects loop, for two reasons:
- I don't really use effects, and when I occasionally do, I really don't use the sort that benefit from being in a loop.
- The amps I like were designed before effects loops were used by guitarists, so it's pretty moot anyway
One of the things I like about those amps, of course, is the power amp drive mentioned by Alan Ratcliffe. And that's something that I like so much, I don't even want a master volume control...