Yes I have a Symphony Pro in my system and I just don't understand. Here at A'gon I've read Audiophiles in these pages wax on about this upgrade, and that mod, or this tweak usually costing thousands of dollars with little to no cost to performance ratio. Bill at Quantum Resonance Technology offers the Symphony Pro for $500.00, you install it on your rack, plug it into the wall and let in warm up at least thirty minutes and prepare yourself to have your jaw drop. Forget about natural timbre, pinpoint soundstage both deeper and wider, better inner detail, lower noise floor, vividness without being bright, better sense of timing, the Symphony Pro does it all in spades, however; its biggest strength is that it just feels right. Piano, guitar, drums, horns, voices they all feel right. If your serious about the music, it' a must have. IMO