I had my Stratos monoblocs upgraded to the extreme mode back in July (I think), and they have their own unique sound. Somewhat tube like to my ears. Very powerfull (much more than I'll ever need), and seem to get faster as they age. Right now mine are waiting on the Candela preamp and maybe some phono upgrades down the road.
If I had a complaint I'd say that it's the total physical size of these amps. They take up a lot of space. But that's about it. My right channel amp has been turned off once for a cable inspection, and the left has never been off. And I might add that if you buy a pair; make sure you have some good amp stands! These amps weigh 75lb. a piece! They fit my current amps stands like a glove, but were bigger than my older ones. If I were to make one change to them I think it would be a switch to turn on the light in the front face as I can see where it might be a distraction when listening to Ray Brown go thru a solo at two in the morning.
gary