I put high priority on the preamp. It is the heart of a great system. I had a Zesto Leto, it transformed my system it is such a great preamp. I am using my back up preamp while waiting for a DHT preamp I'm having built. It's a huge step backward in performance going from something like the Leto to my 30 year old SFL 1 .
Lot's of systems where the preamp is the bottleneck and you'll never know unless you try a few different ones. I was using a CJ Classic 2se , a very good preamp and that Zesto walked all over it. The difference was profound.