Quickly installed the Mercury card and after a couple of minor bug fixes to the code it seems to be working!
Image below using Mercury at 48000 listening to BBC Radio 5 on 909 KHz Medium wave.
Still some work to do, but the basic code is working.
A Console written in Java for the SDR-1000 Software Defined Radio (SDR) and Softrock running on Linux and Mac OS X. A GTK+ GUI for HPSDR (Ozy/Mercuty/Penelope).