The software was to be used with a sound sampler device plugged into the user port. The hardware was never sold, but he provided schematics so people could build their own back in the day.
With the software today, however, you can just load sampled sounds from disk and then edit and play them.
From CSDB:
Incorporated into its operation are many powerful features, such as Cut, Copy, and Paste, which makes editing sound as easy as editing text in a word processor.
There is even a utility included which will convert Amiga sound samples, giving you access to a vast library of sounds.
Probably the most impressive feature of this software is its ability to replay sounds in true eight-bit digital audio on your Commodore 64 without the need for extra hardware. This is made possible by a revolutionary method of controlling the sound chip inside the Commodore 64. The result is crystal clear audio reproduction.
It appears to respond to each SID a touch differently. I needed to increase my "Filter Cutoff" settings to 150 to get audio out that I could hear.
The interface of the program is very slick and highly polished. It honestly feels more like an Amiga interface than a C64 one. It also supports either a joystick or 1351 mouse. I used my Suncom Icon Troller to move the cursor and adjust settings.
Kind of funny. The pointer he designed back then looks surprisingly like someone else's OS 1.3 Workbench pointer.
Now where have I seen that before?