[mythtv] PVR 250 & Sound card issues

[Tom Barber]

Hi guys,
I've installed 2 PVR 250's(both bought at the same time so should be 
virtually identical), in a semperon 2.8 box, with a Sound blaster sound 
card. My primary card works fine with out any issues, but the 2nd one 
works visually but the sound has problems, it works and it doesn't seem 
to be a clipping issue as the 1st card is fine. I've trawled through 
everything and the only matching article i can find came from the dev 
mailing list.
Similar to this: 
http://www.gossamer-threads.com/lists/mythtv/users/71656?search_string=pvr%20250%20crackles;#71656

It works fine for 30 odd seconds then distorts for a few seconds and the 
goes back to being fine again...
I was wondering if this was an IRQ conflict problem, but if anyone has a 
solution please let me know as its driving me nuts.
Thanks
Tom