I'm trying to help but I'm not understanding you.
If your scanners tracking it fine, then what are you needing the DSD for?
The scanner can't decode P25, so he's trying to use DSD to do that. The scanner
is tracking the digital TG, and feeds audio to the DSD decoder.
I'd make sure DSD is actually working, if everything else seems to be OK.
Testing with a P25 conventional channel with fairly continuous transmission
would be good, as you can make adjustments. Problem is, I don't know of
any such channels around Ottawa (which are not trunked, and non-encrypted).
The computing platform for DSD matters; the CPU demand is great and many
are not up to it. I think a dual core CPU of at least >1.6Ghz is required (someone
can help with finer details). Audio into the sound card should be adjusted
independently of the sound card controls (an inline volume control cord should
work).
Dave