I love MIDI Solutions products and have had mostly good experiences with them. I did have a footswitch controller get wonky on me. I replaced it with one from the latest generation that can accept power from a 9V adaptor. So far it's working reliably.

The manufacturers, especially Yamaha, no longer consistently provide power over 5-pin DIN MIDI. So reliable power and ground isn't a given. The "MultiVoltage" devices are MIDI Solutions' way of working around this. Not apologizing for what could be a defective product, but food for thought.