The LR-5000 is a super rare unit. Its considered one of the best quads out there because it had decoders built in for pretty much all of the formats. Especially the coveted SQ-W, which usually required an external decoder. It is built into the LR-5000. This was the follow up to the LR-4000, which did not have SQ-W built in and required the external component - https://www.hifiengine.com/manual_library/lafayette/sq-w.shtml. The 5000 was the way to go in the mid-to-late 70s if you were looking to experience true quadrophonic sound. But dont worry, its also a pretty great 2-channel receiver as well. This one is in great condition. Sounds great and is cosmetically excellent. This sale includes the original user manual which is essential in how to correctly use all the features. Thanks for looking! Heres some more info on this unit: https://www.worthpoint.com/worthopedia/lafayette-lr-5000-channel-sq-full-21305429 I do not have any official quad recordings to test the receiver with but I did test all the speaker outs and they all work. Thanks for looking!