HP PavilionRealTek sound card conflict

I have a relatively new HP Pavilion, using the mobo RealTek sound card
for routine things like system noises, occasional music, etc. Works
fine, and all I need.

The problem is adding a second sound card for use with some ham radio
applications. I use a specialized interface, but in asking around on
ham sites, have found the problem I have also occurs with Creative,
Turtle Beach, and other cards.

If you install a second sound card, when you select Playback, the Mute
All box on the Master Volume is grayed out. You can check and uncheck
it, and the sliders all slide. However, while you can record on the
second sound card, you cannot play through it, and in fact trying to
do so "breaks" the record function until reboot.

If I disable the RealTek in BIOS, or in the Hardware Manager, and
reboot, the second card, now effectively the only card, works
perfectly. So given the above, it appears that the driver for the
RealTek does not play well with other cards. I have the latest
drivers, all the way around.

For now, I have the RealTek disabled, an old card doing the system
audio duties, and the dedicated card for the ham activities. This
does work, but the RealTek provides a good variety of I/O, and works
well, so I would like to get it working. The use of the mobo sound
card and a second card worked fine on my last two, non-HP, computers.
As you can imagine, since it works fine alone, there isn't any help
from tech support. Any suggestions?


--
Alan