Want to upgrade my Adcom GFP 565 preamplifier

I want to upgrade to a better preamp that will not cost over $1200, used. I like my current system but can't help but feeling the GFP is the limiting factor, especially in the high's. Any suggestions for a solid state preamp?

System:
JMLab 806s
2 NHT 10 Passive subs
B&K 202+, High
Adcom 5500. Low
Marchand XM9 crossover
Arcam CD72
JVC 1100