I'm planning on buying a p105 and am not familiar with the USB to Host functionality. All I want to know is if I connect to my p105 to my computer (or iPad) will I be able to hear the synthesized sound coming out of the p105's speakers or will it only come out of the computer's speakers? Any info on this will be greatly appreciated in advance.

Thanks!
Mo

If you connect the USB to a computer, you will still hear the sound from the P150. While you are playing you can capture the MIDI data on your computer with a DAW (Digital Audio Workstation) or sequencer. The MIDI data does not contain any sound, just numerical data, however, that data can then be applied to VSTi's or sound fonts on your computer or a other dedicated software such as Pianoteq.

here's a wiki on VST
http://en.wikipedia.org/wiki/Virtual_Studio_Technology