It is indeed a dsp card but it is no longer distributed by Mackie. It is now distributed by Universal Audio - the company that has developed and manufactured them.
I have a UAD-1 for compression and a Powercore PCI for reverb and some mastering plugs I use, namely the Master X3 and the Assimilator. Both fantastic pieces of kit!
www.uaudio.com
Universal Audio have many years experience of producing some of the best tube compressors on the market. They bought a plug-in company called Kind of Loud Technologies and have since been recreating some of the "industry standard" compressors such as the Fairchild 670 and their own models; the 1176 and the LA2A. I have not heard a professional who has worked with these $30,000 compressors say that the plugs aren't anything but fantastically realistic in their emulation of the originals kit!
Worth a listen if you get a chance!
If you want me to compress some samles that you provide me with I will do so and you can compare them to some compressors you use.
Martyn