The SantaCruz will be a fine card for the SoftRock. The software will
surely work with it as it was the original card recommended by Flex-Radio
with the SDR 1000.
The reason you're seeing a lot of Delta 44 recommendations these days is
that it is the card that Flex is the primary card recommended by
Flex-Radio. It's a 24 bit card and has very good specs. Plus it has 4 ins
and 4 outs which works very will in a transceiver, no need to dork with
mixers and switching when switching T/R.
For sound cards there are really 2 things that will affect how will it
works with the SoftRock and PowerSDR. First is how good a card is it -
S/N, # of bits etc. The second is how good are the drivers. This is more
important for a transciever as it will need to go thru the driver to change
ins/outs when going between transmit and receive. It is less important for
a receiver, but the driver does need to basically work. Most (99%?) of
them do - although there are some out there that will not. I've seen at
least one USB sound card that has a bug that has the left and right
channels off by 1 sample -- deadly for image suppression in something like
My recommendation for folks with the SoftRock is to try whatever sound card
you have on hand. Better sound cards will sound better, but most cards
will work fine given one's expectation for a $23 kit.