Hi Roger,
I advocated that method some time ago ... I got sick of all the converting to Secure SD, 'Checking Out' etc. which is a bit of a pain......
It's a whole lot easier just connecting a standard MP3/WAV/WMA player to the KN7000 (or earlier KNs) Line In sockets.
Admittedly, you need to carry an extra bit of kit to gigs and you don't have the 'Sync' facility, but they are only 'minor irritations'