One additional comment. Back in the days of AM radio being a mostly music medium, record companies would send a promo single to the station with mono on one side and stereo on the other side. Some record companies were a bit on the OCD side about making sure that the proper version was played. The reason being that if you combine the stsreo signals into mono, you lose some of the balance in things. Things that appear in both channels become too loud or too soft in comparison to other things in the mix. That's why a proper mono mix is done for those singles. So, to stop the AM stations from playing the stereo side on mono radio, some would mess with the mix so that it didn't sound right when combined to mono. A good example of this is "I Fought The Law" by the Bobby Fuller Four. The stereo mix on the promo singles had one channel inverted. The result of this was that when you played this stereo side in mono, the vocals disappeared and you had an instrumental version. AM radio wasn't interested in playing rare mixes, so an accidental instrumental was a horrible thing. They wanted to play the hit, so they'd turn it over and play the mono mix. :) Talk about being control freaks! Dave