I think JRiver stated it pretty well: Jplay is a Hoax
Oh, by the way, I got a lifetime ban on Computer Audiophile for pointing out that one of those (with "inner rendering loop optimized by ear" was claiming to be open source, but refused to release the source code (that was based on another open source software player) for public scrutiny.
“Julf - When your CA membership was reinstated you agreed not to engage in unprofessional behavior. Based on a review of your posts since that time I believe you've violated that agreement. A warning simply doesn't go far enough. I've decided to ban you from the CA forums for good”