Yeah, I probably should have been more descriptive. From what I have read, folks universally report a noticeably improved quality in sound with the YOP 1. Plus the ability to bypass a step down converter. I would have to let someone with experience chime in to add more detail.
I doubt I could build one myself. Apparently there were very good generic versions out there for much cheaper than I have seen, but they seem to be scarce now.
I'll be sure to check these out on Japan Yahoo like you mentioned, just to see what going prices are