Thank you for your interesting answer, Pasquale.
I, for one, turn it on and off with the headphones plugged in BUT with the stepped attenuator at its minimum volume position. I certainly wouldn't recommend plugging or unplugging the headphones while the amp is on with single-ended connections.
Balanced connections should allow you to do that (I guess, I'm even not sure) but single-ended ones cause a short-circuit in the amp while plugging and unplugging. With a fairly low impedance output amp like the Soloist, I suspect it really could damage it ...
Thank you once more for exposing your point of view, always interesting to share information !
Edited by CoolBurn - 4/9/13 at 7:49am