First Post, Looking to buy Amp& Pre, $7,000

The first thing I'd like to say is "Thank You" to all the people on this forum for their knowledge! I've learned so much from my daily trip to this wonderful site.
The reason that I,like many others I suppose, have not posted before is that I think there are so many people here that have so much more to offer in knowledge and experience than I do. Well..... on to my questions.
My system consists of PSB Synchrony One speakers, A VPI Classic tt with a Dynavector 20XH cart. A Simaudio LP3 phono. Cambridge Azur 840 CD player.
My current amp is a Denon AVR 4806,that also doubles for Home theatre.
My current system sounds very good, But.... I'm wondering how much better could it get? Will new amplification be a huge improvement over what I've got?
I would prefer to buy used because I think I could get more performance for my money.
I listen to Rock,Classic Rock,Blues, and Jazz.
I would prefer a sound that is neutral,but a shade on the warm side. I suffer from tinutus in my right ear.and any high notes that are too dry, or too bright, irritate my ear!
I also need a pre with HT bypass,as I have everything in the same room
Thanks,
Mark