The portable you probably heard of is the Optimus CD-3400. The other only superior CD portables soundwise are the ironclad Denon DCP-100 and DCP-150. Do note that all of these are discontinued, but you might have luck looking around for some.
Best Sounding Portable CD Players???
I just bought a used Headroom Cosmic headphone amp with the BaseStation power supply upgrade through an auction here on Audiogon. I am looking for advice on the best sounding portable cd players out there to replace my 10 year old Sony. I will be using Sennheiser 580s with this setup. Headroom recommends the Panasonic SL-SX460, and I remember reading something in Sensible Sound a while ago about a good Optimus unit, but that's all I know about portables. Any advice out there on portables I should listen to?