While I'm not sure when if ever I'll need to sum an iPod's headphone output to mono, I can certainly appreciate the desire to have a simple 2-in mono summing mixer in my live rig. For the time being, do yourself a favor and ignore the obvious marketing ploy behind the Whirlwind PodDI, and come up with a list of all the other things you can do BESIDES introducing mono-summed, lossy audio into your mix. I mean, c'mon.