Subsonic Filter

[Pim]

With my Dynaudio C1's, and SAM on, the bass drops off when I turn it up too loud so it must be the protection part of SAM that does that. It would be interesting to know what creates the low frequency noises on your track Confused. Have you tried listening through headphones? Is it part of the music? (i.e. does it come with a rhythm or is it random)

I said in my original post that it looks like the kind of environmental feedback that you get with vinyl.  Thinking about this today, I'm wondering if this is exactly what it is.  Not from my turntable, this is a CD rip, but from one of the turntables used to actually perform the track in the first place.  This very likely went unnoticed in the studio, with normal speaker low frequency roll off, but with SAM pushing subsonic stuff to virtually flat  / zero roll off, then the effect is exacerbated and becomes very apparent.

There was a story going around at the time that Philips introduced the CD that they had made a recording that had some sort of rumble that they couldn't quite identify. It turned out that it was a train or subway that was close to the recording studio at the time of the recording. Of course it could just have been made up by an advertising company... Maybe you could sell your 'problem' to Devialet to be used as a sales pitch