QUARK is based on the 1970s Sansui QS Regular Matrix format. We based most of our work on the 1974 AES whitepaper. There are many popular releases mostly from the 1970s. This website has a pretty complete list. The ones that are relevant to this format of quad are labeled “QS” on this page. Some of these releases also have alternate stereo mixes but many were only released in QS. The beauty of the format is you don’t NEED to have separate mixes.
One of the QUARK developers recently produced the first quadraphonic vinyl release in 30 years with Suzanne Ciani’s LIVE Quadraphonic. Work on that record is what lead to the development of QUARK. Impulse Records famously exclusively used the QS format for a period of time. The sad thing is most of these releases aren’t properly labeled. For instance there is a beautiful piece by Michael White in this format.
Pink Floyd’s “Dark Side of the Moon” is an example of a recording that had both a stereo and a quad mix. To further confuse things, it was done in the competing SQ format. Someone re-encoded the song “Money” in the QS format.
In addition to vintage and modern hardware decoders, you can listen to these songs in quad using the “decode” function of QUARK by routing the audio from your playback browsers through your DAW using an application like Loopback (or similar).