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?