One day a lonesome dbx noise reduction unit was spotted upside down in a rack by these two. This hallowed name, spelled as it is in lower case letters, in its upside down mode reads "xqp." A.J. and Dane found this to be extremely funny for some reason, and immediately adopted it as the name for their new phono preamps.
Before long, every blank panel in the racks of the entire facility was sporting a new splatty paint job and an XQP name and model number. This was all in good fun. There were also a host of JBL 4350 cabinets built one day with the XQP logo attached. Read all about it here. There was even a wireless AC receptacle.
Moving forward ten years, Dane designed and built the Dane #31 Optical De-esser in half-rack format and with built-in power supply. It all started rather by accident, but it proved to be a nice-sounding unit. Some engineers considered it to be the best de-esser ever built. However, production ceased within a few years due to a number of life's complicated issues. Several more were built in the subsequent years, and a small number may still be built in future until the metal parts run out.
So the 531 evolved from the #31 as a VPR unit, a couple of small changes were made to improve consistency and stability, and then A.J. Wells came into the picture again after many years. Thus XQP was officially formed after 29 years of nonsense, and here we are building things for real.