Integrated amp for Vivid 1.5

I'm looking for an integrated amp to replace my Plinius 8100. Speakers are Vivid 1.5, and room size is 10x10x8.
1. Budget is $2500. I'm looking for a step up from the Plinius 8100 level, therefore I'm looking for either used or demo unit (that retail price is around $4-4.5K).
2. I'm  listening to Classic, jazz, vocals.
3. I'm not replacing audio gear very often (I had my Plinius amp for 17 years), therefore I prefer having an amp with High build quality.
4. I never had Tube amp before, and I read good things about Prima Luna amps (both for sound and build quality).
Does anyone heard Vivid 1.5 with Prima Luna gear?
Any other suggestions for an integrated amp in this budget?

System source: Logitech Squeezebox touch with Teddy Pardo power supply.
DAC: PS audio Nuwave (old version without DSD capability).

Thanks for your help.
Thank you for the detailed answer. 
I will PM you with some more questions.

I also have the Primaluna and about 4 months ago retubed with the kt150s.  The sound is incredible.
Your description of them running "cool," prompts me to ask; how cool?
On my rig, the 150s are noticeably hotter than the EL34s they replaced.
Thanks in advance,
I started with the KT 150s so I can't compare to the EL34s but they are cooler than the KT88s in my Cary. You might want to give Kevin a ring if you think they may be running hot as they are expensive to replace.