I listened to "Someone saved my life tonight" on the SACD, via the analogue stereo outputs on my Oppo 203 through the SM2 in Involve 4.0 mode from the
Stereo layer and the Multi-channel layer downmixed by the Oppo to stereo (in case it would show up something). Then directly as the SACD stereo and multi-channel without the SM2 in the path.
My speakers aren't that far apart as the room is only 3.8m/12.5' x 3.6m/11.8', but I walked round sticking my ear next to each. If there was pumping I would expect to hear a whooshing in the audio, and/or a 'disappearance' of some of the audio in that channel, or when in the centre of the room a shifting/'bouncing' of the audio 'image'.
I couldn't identify any due to the SM2.
But, its an early/mid-70s recording and the drums & percussion are distorted, as are a few instruments. I could hear what I think is compander pumping in the original album directly from the SACD and more noticeable in the multi-channel. So to limit peaks or to create an 'effect' the signal is passed through an envelope tracking compander on the mixing desk either on record or during playback, sometimes with a noise gate. What I think I can hear is some envelope tracking giving a pumping 'sound' on the drums and percussion due mainly to tape hiss in the Left channel in stereo or left front in surround. However this is present no matter how I listened to it, it is probably slightly more noticeable in the SM2 Quad synthesis mode.