Further to my recent request for help after I damaged my laptop's 
sound card, I now have a solution that works.

My first fix was to buy a VERY cheap USB sound card (GBP2). This was 
OK for headphone output, but did not work at all when my receiver 
audio was connected to its input.

The second one was a slightly less cheap USB card which worked but 
with a lot of jitter on the SecLab display. I suspected that the 
problem was my USB1 port.

Next I bought a USB2 port that plugged into my old laptop's PCMCIA 
port. This improved the jitter, but it was still unacceptable.

The final fix was to buy a high quality SoundBlaster sound card that 
plugged into the PCMCIA port. This is a really nice piece of kit and 
has solved the problem completely. The cost from an eBay auction was 
GBP28.

Thanks to all for the advice. I am now QRV again on QRSS and VLF.

Mike, G3XDV
==========