For your continued "fizz"/"sizzle" that has remained through multiple FRFR speakers:
1. Check your guitar- if it's old or made in china, you might some wiring/grounding problems that make noise
2. Check the obvious things on the Axe: input level, input trim, output level(s), etc.
3. Check your cables- bad cables make for bad noises
4. Check your room outlets- if your house has bad wiring, grounding, or inconsistent voltage, you might be getting noise from there
5. Unity gain- do as best you can to get ALL your gear volumes at noon (FRFR volume, axe output, axe input, amp ctrls, cab level, etc.)
6. Make sure you just do a simple patch (amp/cab/rev) with as untouched ctrls as possible.
7. Try another fx processor thru the RCF's at Guitar Center or some other store- it could be your hearing. I know lots of musicians with "artifacts" in their hearing for various reasons.
That's all I've got. Hope it helps.