Using this to send one output of a Midiface 4x4 USB device to five mono-timbral MIDI synths (mix of old and new including DX7, Model D, Electribe EMX). No issues or lag as far as I can hear.
Powered by a standard iPhone charging plug (not included) via a small USB cable (which is included). Unit is as small as it can be and very light, but feels rugged enough to gig with.
**Edit a few months on: I'm having trouble with a few synths to the point of uselessness. Korg Monotribe, Behringer Model D and Sonicwear Texture Lab all exhibit stuck notes when connected to this MIDI Distributer, the Pro800 in particular also having missing and/or late notes. This happens when single or multiple synths are connected with a range of DAWs (Logic, Studio One, Reaper on Mac and PC).
On the other hand, I've used other synths with no problems (Korg Electribe MX, Yamaha TX81Z, RX17, Behringer RD6 & TD3, Nord Micromodular). In other words, YMMV.