Hi MDX-400 i have this same model which i have been using almost daily since it was released, it was the top end model at the time and still out performs anything i have looked at since.
Great feature is that you can plug the USB cable into any computer at use it as a sound card for that computer in PC mode.
MD always sound great and being able to use optical cable from my Mac Book Pro's headphone jack to record to either the MD drive or to my DAT recorded is great.
You have a good unit there well done and enjoy.
Dale.