I searched and just found out it means the sound will be lush and the tubes will get very, very hot.
Anything else I need to know.
I'm considering one of the Woo Amps and one is OTL and the other is not.
I picked up a Predator to use at my work station.
(There's no room for a full size amp)
I was skeptical at first.
My ED9's sounded great straight out of my Macbook, but the amp really does open it up and tame it down.
As some have said- the portable amp does not add much, but it's enough to notice and I prefer to listen with the amp.