Originally Posted by steve392
I don't have a sound meter but I am sure i will get one if it helps
It will definitely help as I doubt there are any who can accurately set their subs by ear and do so without first having benefit of a sound level meter to teach them what to listen for.
After going through four sound meters, this is the sound level meter
that I finally settled on as I wanted a sound meter that was held to a minimum, Type 2 standard, could be easily calibrated at home, had a back lit display panel and a usable low of 30dB. Personally, I wanted better then is expected from the forum standard, the Radio Shack, digital, sound meter,
which I also have and have used. The price is about the same.
As was suggested above, a USB microphone
coupled with REW (freeware)
is a good room measuring package (inexpensive) so one can see how subwoofer placement/settings affect a subwoofer system's interaction with a room's acoustics. Taking these "heroic" measures, assures one of getting the best out of their subwoofer system. When I post getting the best, that does not mean perfection but instead means getting the best out of what one has.
To get the best out of one's system (close to perfection), one may need an additional third or fourth sub (and possibly the addition of room placements) as two carefully integrated subs isn't a guarantee of perfection but with effort, my educated guesstimate from personal experience, one can expect seventy to ninety percent efficiency, depending on how much effort they're willing to expend. From there, more "heroic" efforts will need to be made via the addition of a third/fourth subwoofer and/or the addition of room placements to attenuate (absorb/smooth) reflected sound waves, preventing issues of reinforcement or nullification.
In our case, I feel we've gotten the possible best out of our two subwoofer system (yes, I'll keep trying) and room measurements show empirically that we need a third sub if wanting a better response to our subwoofer integration efforts. In the end, it all boils down to the user and how good do they want their room to sound.