Raspberry Pis work very well for this.
I was up late last night turning a Pi into a MIDI repeater, and the results are excellent. I haven’t used @sinedied’s code yet, but that looks like the quick and easy way for people who don’t want to fiddle with Ruby and shell scripts.
Unfortunately, with Pi prices and availability as they are you are probably better off with an RK-006 unless you already have a few Pis on hand (as I do).