Why does JK offer a different device for In and Out?

[mark@butterill.plus.com]

This was indeed the method we have tried to use for our bass player. He plays through a Line 6 HX Stomp which can act as the input interface, however there's no return signal route so initially when he had headphones plugged in to the Stomp he was direct monitoring and out of time to the rest of us. Using his Windows laptop audio output for the headphones, and the laptop's mic for talkback seemed to work but over two sessions he was plagued by gain issues - his bass would sound great to us, but would distort through the laptop audio system so it sounded awful to him. Or his mic would distort to us. It just didn't seem possible to get the gains balanced across the input and output, so he's now ordering a 2 channel interface to set up the same as the rest of us.
By the way our guitarist had the same experience trying to use an Apogee Jam for input and his Macbook output for monitoring and talkback. Unworkable for us. Great news for Behringer interface sales though!