This is one GREAT little MIDI<->USB converter
For AZSMZ opto isolated USB MIDI Converter
I have been looking for some inexpensive MIDI-to-USB converters, as the wires seem to have broken on the two I have. The nice thing about this one is that instead of permanently attached cords that can't be replaced, this board actually has high-quality JACKS for you to plug in your own USB and standard MIDI cables. Not only are separate cables usually higher quality, but if there is a break of problem with a cable you just unplug it and plug in a new one!
I am VERY impressed with the quality of this little board. The connectors feel very solid. The soldering is SUPERB. The components look 100% quality and the PCB quality is excellent too. As far as I can tell, it is completely MIDI USB class-compliant, so no drivers are needed. I've tested it on Windows, Mac, and Linux. Currently using it on a Raspberry Pi. I have never seen a dropped note on, note off, or other message, and nothing important seems to be filtered out. Basically, *pure* MIDI to USB.
You can't find anything this good for the price on Amazon or eBay. I am ordering 2 more right now.