Your amps are great, speakers are great......I'd get a high quality tube preamp. For me it brought my entire system together, like 1 + 1 = 3 or more.
I didn't see your budget, but here are a few I'd consider (For full disclosure I own the Aric Audio Motherlode XL, as I wanted fully balanced throughout. I've tested each of the below preamps in shops, in friend's systems, and I've had them on loan in my own system.....They are all brilliant preamps, I prefer the Aric Audio and Raven preamps; but some will disagree.
Aric Audio Super 6SN7 $4,675 or Aric Audio Motherlode II $5,750
Don Sachs/Lynn Olson Raven preamp, sold by Spatial Audio $6,395
Backert Labs Rhumba Extreme 1.4 $8,500
Supratek 6SN7 Cabernet $4,000
All of the above rarely are found used, and if they do show up; they sell very quickly

