ROCKPAGE

Vox made headphones- amp simulators with an imput for external mp3 device. You just plug in the headphones to the bass (they also make it for guitar) and done!

For me, it's the most confortable system for touring and re-building the board, routing pedals, even changing order of them, etc... I'm endorser of the brand and as far as I know, they put all the love in the design and developement of the boards. There are some pics of my mounting process: Aclam Sm...