My Axiom M3V3s gave me too much bass in their corner locations that artificially reinforced bass. EQing helped somewhat but was far from ideal as other freqs were affected as well.

After reading an article here on port plugs, I made a couple of plugs that sealed the M3 rear ports & completely solved my problem - nice, tight bass now in the correct amount.

Unfortunately that might not be an option with yours as the PSB's port appears to be rectangular on the front.

Good luck with your problem...

TAM