This might sound stupid, but could the speaker stuffing be affecting the airflow...like blocking the port? Anyhow, I agree with Ken...if the airflow isn't affecting the sound quality, I'm not sure you should be too concerned.

M60s
VP150
QS8s
Marantz SR6003
Samsung LN52B550
Oppo DV-980H
Insignia NS-WBRDVD