I'm using Karan amps with a BAT pre-amp. The Karan stays on all the time, and is just warm to the touch. You might want to look into a demo to determine whether it fits the bill. You might also consider Hovland and Gryphon. If you have alot of extra money, Dartzeel monoblocks. For tubes, perhaps CAT or BAT monoblocks. Not sure about Krell with those aluminum cones. Also, would probably not think to use Boulder, Halcro, or Edge. You need something with some fullness in the midrange, even with the tubed pre and DAC. BAT VK-600 and McIntosh might work.
BAT SS amps VS Ayre MX-R
I have a BAT VK-250SE with a VK-52SE preamp. I'd like to try a different solid state amp and eventually preamp to go with my Hansen Audio Prince speakers. I think the Prince's would benefit from a more high powered amp. I like the overall sound of the BAT equipment. I've considered the VK-600SE. I'm just alway interested in something different and maybe better. I'd like to hear form anyone with experience with either BAT or the Ayre MX-R amp or any other suggestions. With the Prince speakers I've left the upgrade path. I'm looking to do the same with my electronics. My front end is a Modwright Truth Transporter with Vintage tubes. I'm very happy with it.