I am a big fan of VH Audio... The AirSine is awesome if you can afford it, but the Flavor 4 is also an excellent PC and works extremely well on digital gear (at least for me ;-)
I've also recently purchased two Black Sand Silver Reference power cords -- one for amp (McCormack DNA-500), one for preamp (ARC SP9) -- and I have to say that these are really stellar power cords that compete with the best I've heard. There's also an interesting thread out on AudioCircle.com about Black Sand in the Critics Corner worth checking out.
Both VH Audio and Black Sand offer evaluation periods. Black Sand is currently running an auction for the Black Sand Silver Reference.