For my guitar I typically use my Boss TU-2 tuner to send to two amps as it is last in the chain of the few pedals I use. It has two outs; one goes silent when you engage the pedal and the other does not. It has worked very well, but I want to setup my harp to go to two amps as well and it got me curious as to other options. Smallest footprint etc., that does not hurt the signal. I also use a Radial Pro DI Direct Box for a lot of different 2-to-1 or 1-to-2 functions and if there is something smaller and cheaper that works, I'd rather not tie it up.