Summary:
I have to agree with Jack. A very worthwhile upgrade if you have the quality of kit to match. The more transparent your system the greater the improvements will be. I found that the bass dropped an octave, the soundstage was thrown deeper and wider, and the sound took on a more appealing feel. The hardness had gone, replaced by a sweeter, more inviting sound and now i can ,listen for longer periods without it becoming fatiquing.If your system suffers from prominent brightness or 'edgy' sound stick one of these under your cd player and see what happens. If you can afford it get one under the amp aswell. A worthwhile upgrade in a modest system.

Summary:
Got this to put under my amp(Jadis DA-60), due to the fact that I liked the CD sink Under my CD player. The effect? Quieter background, deeper bass, overall much smoother and relaxed while haveing more detail. The subjective volume seemed lower, despite the gain was set the same. The soundstage suddenly became HUGE! I honestly was not prepared to hear any difference, let alone this much. I would rate the change comperable to a component.I admit it is an expensive Tweak, but well worth it if you can swing it. In my situation, I have to give it 5 stars anyway.