I have a ThumbDV here, which is an AMBE3000 chip mounted to a board
with USB interface.
http://nwdigitalradio.com/wp-content/uploads/2012/04/ThumbDV-A.pdf

On the computer, it is accessed with a serial interface, or let their
ambeserver software handle the serial and communicate with ambeserver
over the network.
http://nwdigitalradio.com/dv3000-ambeserver/

Has anyone tried integrating this with OP25?

The primary system I monitor is P25p2 (TDMA), but I am curious about
DMR and Dstar as well.

My goal is to offload voice decoding to this hardware for CPU savings
so that lower power systems can be supported. I am also curious if it
will improve voice quality, but this is secondary to CPU savings.

Has anyone profiled OP25 to see where the CPU usage goes? I'm curious
how much I could really reduce it by offloading voice decoding but not
RF demodulation. I suspect it's working pretty hard on RF demod.

If no one has tried this, can someone at least point me toward the
right part of the code to inject support for alternative decoders?

Tom