Sub Integration

Here's my system...
NAD C375BEE integrated amp
PSB Imagine B speakers
2 Klipsch 10" powered subs
Outlaw ICBM Bass Management
For 2 channel music only (not HT)
My listening room is 15' X 20' with plaster walls and carpeting. I have experimented with moving the subs at different locations and sub output volume .The Outlaw crossover is set at 80 Hz to handle lows below the PSB capability (52 Hz). While the mains still sound good the bass from the subs still sounds what many would say is "boomy". I do not have an SPL or any room correction equipment.
Any suggestions as to what I may try next?