A more standard approach would be to use a Mini or Pro with the E50 and the Yamaha. I use a Pro with my E50 and it works very well. For what it's worth technically what you are suggesting will probably work using Usb out from the Amp, whether the Wiim Amp to E50 to Yamaha would sound better than the Amp alone would be your decision. However, it really does seem an odd direction to take unless you have all of the kit sitting around in your house to try.