I may quote from another well-known forum:
Gardo wrote: I have a Polydor WN (813651-2) from the very early days of CD (copyright 1983), made in West Germany, bought in the States, and it clocks in at 43:25. It is (obviously) NOT Steve's remaster, though it does pass the one-channel BBE test described above. It sounds like it was mastered from a third or fourth generation tape: hissy and congested. Another tell-tale difference from Steve's: "Baba O' Riley" is faded in, taking about 3 seconds to reach full volume. On Steve's master, "Baba" is NOT faded in.
I assume this is incorrect? Well, my Canadian CD of Who's Next meets all the usual criteria for having Steve Hoffman''s master, but "Baba O'Riley" is faded in. Not sure if it takes 3 seconds to reach full volume, maybe only 1.5, but a fade-in.
Do all versions of the original mix have the fade-in?