How to select and pair a preamp and power amp?

I'm considering returning to a pre/power  configuration after years of using a tube integrated amp. I will likely buy used and my budget is $5K. I have Focal Be 1038 speakers, they are efficient but do benefit from power. So what makes better sense, finding the preamp first or the power amp first. I'm at the mercy of the used market, timing might dictate the whole process. Also, any suggestions of tube/SS pairings with proven synergy?
I think most will probably recommend first choosing a power amp that best matches the speaker's characteristics and then pick a preamp that has the best synergy with the amplifier. The size of the room and the listening volumes also play into the decision, in my opinion. I've not heard your speakers but the specs, particularly the impedance characteristics, seem to suggest that they would benefit from a moderately high powered solid state amplifier to show their potential.  
At your budget I’d rather focus on quality and stick to integrated—neglecting need of extra ic pc etc. Maybe look to step up in quality from your current unit. Perhaps integrated from Accuphase, Luxman, Pass which I’ve heard (at friends/dealers) paired nice with Focals would work well. Goodluck.
if you use multiple sources i suggest finding the right preamp that suits your needs and built around it