Could use some help with a tough match

I currently have a pair of Threshold SA 1's which have been completely rebuilt. My challenge is to find a preamp to create the right synergy with my Sonus Faber Amati's. I would like to try a tube preamp but the Threshold's input impedence (75k) and its unbalanced inputs are making it very difficult to find a match. Has anyone out there had any success running the SA 1's with a tube preamp ?