Heck, just download some free software, and run the audio through
your puter, if you want to give it a test drive. Those DSP's seem
to be as good, or even better than the outboard hardware versions.
I use SBFFT, MM-DSP, etc. Chromasound is pretty good for payware.
They have a free demo which runs 15 min a shot. You have to restart
it after 15 min...It's pretty good.
Some do some things better than others.
SBFFT is good for making "brick wall" filters, and can run up to six
filters at once. It's a DOS program though. No problem here, as I still

run win 98...
The others are good for all around filters, and NR.
I have DSP built into my ic-706, and my DSP on the puter is much more
powerful as far as bandpass/stop filters. Chromasound has autonotch.
In fact, I've compared the auto notch in the icom, to chromasound,
and there was no difference I could tell. You need a full duplex
soundcard to run these. Myself, I've got DSP out the kazoo,
and hardly use it...
I think it's overrated... Sure the NB works, but it muffles the audio..
The autonotch works great, *until* you started having SSB voice on top
of the heterodyne, and then the autonotch gets confused, and pulses
on and off between words...I prefer the fixed notch in my 830, or
even the fixed DSP notches in the puter software.....
SBFFT is great for taking razor thin slices out of a bandpass...IE:
a heterodyne on a MW station, etc...
When I'm on 160m, and trying to cut noise to hear super weak sigs,
do I use DSP?
Nope...I use my variable bandwidth filters, IF shift, and manual notch
thats on the TS-830. That combo is better than DSP, more adjustable,
and molests the desired signal less. MK