The smoothest amp you've heard?

What's the smoothest amp you've heard? I'm talking something so smooth it was perhaps too smooth, if that makes sense
A very nice amp and definitely the smoothest amp I have ever owned was the Luxman M800A. I've owned 36 amps since 2006 (which does not make me any kind of expert, but it does make me psycho!). Certainly the Pass amps I have owned were very smooth as well.
And then I've had some some fingernails on chalkboard amps as well. eewww
Ok, if you don't want smooth, go for jagged, rough, harsh, unforgiving. 
Your choice.