The HHb MDP500 Portadisc (late 2000) is a rare and interesting "portable" pro-level recorder. It's huge because it's based on a home deck mechanism, not a portable one.
It's a physical giant, dwarfing my Sharp MD-MS200 slot-loader! It's festooned with buttons and controls and also features a large, backlit display. The inputs/outputs are phenomenal including a full-sized headphone out, optical in/out, and XLR mic inputs. There's a USB connector, but it's not for NetMD, but rather real-time audio. I'd assume like a USB speaker connected to your PC.
I was sent this one because the owner wanted to see if it worked but didn't have the proper powersupply. Also, the 8AA(!) battery holder that it came with was cracked beyond repair.
After using this universal adapter, I was happy to see it was working fine, but since it was 20+ years old, I decided to open it up and clean it. Check it out if you'd like to see the insides of one of the more rare recorders out there.
Universal Power Adapter - from Amazon (these purchases help me buy more MDs if you end up buying one)
As always, check out the video to see it in action.