Does anyone have any advice on a good attenuator for a Peavey 5150 that doesn't suck out the tonality of the amp?
A Weber Mass of some sort...
I've heard nothing but good things about them, and currently after one myself.

Epiphone Les Paul Standard w/ SD Alnico Pro II's
Fender Aerodyne Telecaster & Stratocaster
Marshall JCM 800 4104 combo

E-Married to Funny_Page
check out www.eurotubes.com they have some good attenuators
Agile Septor Elite 7-String
ESP H-1007
ESP H-1001
Peavey 5150
Mesa Boogie Cab

Recording Gear -
PreSonus FireStudio Interface
CX5 Studio Monitors