I'd like to find a datasheet for an audio ADC used in an inexpensive
USB audio capture "card" so as to better understand how to use it and
what it can do as a low-frequency oscilloscope. It came from Amazon,
sold under the name "DIGITNOW! USB Audio Capture". It seems to work
surprisingly well, working with no issues on a Raspberry Pi 4 using
the stock RaspiOS version of Audacity. It also works under the latest
(not stock) version of xoscope, which had to be recompiled to obtain
ALSA support. I'm inexperienced with both programs, so the behavior
is somewhat confusing but it does seem worth exploring further.

The seller's tech support carefully misunderstands every question.

It's a one-chip dongle, the single IC is marked
IS821S
SHO3AO9OAGC
1O2DNMO19

All the O characters look the same, so they could be mixed with zeros.
Repeated searches using Google and DuckDuckGo have turned up nothing,
does anybody recognize at least a manufacturer?

Thanks for reading!

bob prohaska