I was in your position just a short while ago and bought the Signal Cable magic power for my NAD C372. Brightness in a system bothers me a lot, and I wouldn't describe the Signal Cable as bright at all. What I did notice was a tremendous increase in resolution, top to bottom, with a lower noise floor with increased micro- and macro-dynamics. There's increased resolution in the treble, but without a touch of emphasis.
All that said, I haven't tried the others you mention and would be curious about others' views on them. I'm happy enough with the SC that I plan to buy two more--for my power conditioner and the CD player that's plugged into it. The rest of my system for reference: Vandersteen 2ce Sig II, Sony Playstation 1, APC H10, Tributaries and Monster cabling.
All that said, I haven't tried the others you mention and would be curious about others' views on them. I'm happy enough with the SC that I plan to buy two more--for my power conditioner and the CD player that's plugged into it. The rest of my system for reference: Vandersteen 2ce Sig II, Sony Playstation 1, APC H10, Tributaries and Monster cabling.