I've been away from home for work about 1 week and the first thing I did when I got home was fire up the HiFi. To my horror the 2nd track I listened to had this odd noise. I initially thought something was rattling on a shelf but it seems to be coming from the ports. I don't really recall hearing it before I left but I'm getting significant noise from the ports. I'm pretty sure it's due to the air turbulence of the port which I believe is text book "Chuffing"?

The track was "It Could Be Sweet" by Portishead, which is very bass centric. I don't really notice it with other tracks.

In total disclosure, the day before I left I was doing some measurements and messing with subwoofer phase. I had played Pink noise and set volume to ~85db. I then played a 50hz sine and adjusted the sub phase until reading the highest SPL at the listening position. I definitely heard significant port noise while performing my measurement but I kind of just wrote it off due to the sine wave.

I also spent some time setting a PEQ on the sub to help tame the room mode @ 55hz, I unfortunately have no way of doing anything for the mains at the moment.

All of my amp's tone controls are bypassed via a "pure" switch on the amp.

I didn't really get a chance to evaluate anything I was doing before having to leave town.

Anyone else able to evaluate this track and notice anything....?
Could I have damaged something by playing a sine wave for an extended period?
Could the room mode be contributing to the noise?

Larger
Round 4.jpg