I had a similar problem. I had to employ bass traps which corrected my issue. However, it does take some tweaking to get it right. Try playing with some sound absorbing materials, like a pillow and place them in the corners near the M80's. Then retest, if it gets better then you should look into bass traps

Just a thought…


Tom

M80's VP150 QS8's Earthquake SuperNova MKV-15
Integra DTR-7.4 Outlaw 755 Outlaw M200's Outlaw ICBM