Thanks for that Alison. The bandwith of the board (as supplied) tops at 1800Hz, Hans suggests that ssb should be okay but am I wrong in thinking 2400 would sound much different?

I would be using both methods of reception, I Q into my pc and polyphase when mobile/portable.

Not sure if any other polyphase users have carried out mods to this board. Guess I'll wait until its fully assembled and use the monitors either side of my head, hi.