Upgrading from Integrated Amp to Separates

I have a Primaluna Dialogue Premium HP integrated amp now, driving Harbeth M40.1's.
I like the sound, but am considering upgrading to something more powerful and with greater finesse.
I have had solid state gear in the past and have always come back to tubes, so I think I want to stay with tubes.
I would like to get a stereo amp (no monoblocks) and match it to a very nice preamp.
I have been considering Balanced Audio Technology gear but beyond that I really don't know.
For my budget, I would prefer not to go over $10K total for both components.
I am in no hurry to make this change, just thinking and doing research right now.  I am willing to take more than a year to decide if necessary.  
Please give me your suggestions.
Thanks!
Peter