Remember test records and alignment tapes? Dark Side made an excellent test record if you had good ears and knew what to listen for. That notion hit me when a friend played it for the first time on his premium system in a great acoustical environment and I noticed that opening heartbeat sounded like crap, also each woofer sounded different. (15" Altec-Lansings in sealed enclosures) The next day I brought over my HP 200D generator and fed them 20Hz at some decent volume while working a lit cigarette around the seams. Sure enough it blew around in a few places so we took the speakers out and sealed the seams from the inside with silicone bathtub caulk, problem solved. That reminds me, on a good system you can pick out several sloppy edit points on Great Gig In The Sky where they spliced three takes of Claire Torry's vocals together.

Oh, when da Bronx be burnin' open da window an' bree deep. It be da ganja mon, feelin' irie!