Well, that depends how they're designed and your rig. Many amps don't sound good volume down and some do, regardless of wattage.
Most of distortion in TT, for intance, is from PI before master volume. Works fine with low volume, if you can get that single knob tone stack to work with your rig.
I just yesterday wrote review here about my new Egnater Rebel 20w, which really sounds just as good with master volume at home practice levels as at noon.
I don't believe in digital cab sims etc... They might sound good, but I don't like them.