Octave Integrated Amps

That will most likely depend with which integrated you are using and with what tubes. It will also depend how efficient the speakers are too. Also what is too loud for me is not loud enough for my son. EL34's don't have the power 6550 or KT88's have. I have the V70SE driving 85db Dynaudio Signatures. With the volume control at 10 o'clock is plenty loud for me. Lately I've been rolling 6550's - KT88's and KT90's. I haven't had the EL34 in for several months now but they have a lower power output (but a mid range magical sound).

That being said I recently had a V40 in my home and the power did not seem to be any less than the V70SE.

The V40SE will handle 100db speakers with no problem. My only concern would be the impedance dips below 4 ohms. The Octave will do 2 ohms but at that point you are pushing the integrated to the max.

As far as the volume taper, I find my Ei KT90 type 2 output tubes have the shallowest but at the same time are one of the more powerful tubes I have.