Woofers pumping

Check   speakers wire connectors , 

@tomcarr Its very obvious the problem is either the preamp or your source. 

Hello @atmasphere !

I don't think it's  the pre or the source because I've had  two different preamps, and two different sources, and it has happened with both configurations.

It only happens when listening to two songs, out of the thousands of songs I listen to.

I'm of the opinion that there is some subsonic bass buried in those specific recordings.

Thanks to all for your opinions!

@tomcarr The way you were talking about this in your initial post, I got the impression you had a problem with motorboating, which is where the woofers pump on an on-going basis.

But if it only happens on certain tracks then the system is just doing its job so no worries. 

Thanks @atmasphere!

Always appreciate your posts.