On the subject of speakers though I have a pair of JBL studio monitors (LSR 308s) and have spent a considerable amount of time researching optimal placement, breaking out my tape measure and trying out different spots in my monitors and chair to help get the low end under control, my "office" is in a pretty small rectangular room so the acoustics are bit **** but by applying the 38% rule I've vastly improved the frequency response, when I had my speakers much closer to the wall as well as my desk there was a pretty big valley in the 100-200hz range and a big peak around 45hz, didn't sound horrible without something to compare to but when I would swap to my headphones I would notice all the missing frequencies. I record music and I struggled with the mix on my bass guitar as certain notes would be much louder so I'd have to use my headphones to check how the bass mix was.
While there are several ways to linearize bass with loudspeakers - it's almost always a crap-shoot for any given location. You've got not only modal problems, but also floor-bounce problems. The most consistent method to linearize this problem (across most of the room) is by using multiple distributed sources. Basically several "subwoofers" with a higher freq. low-pass filter (say 120-150 Hz depending on the order of the low-pass filter) placed rather randomly in the room. The "subs" should be direct radiators (not "band-pass") and they don't need to go that low in freq. if the room is small (38 Hz should be fine). I call this the Geddes method, as he was the principal person advocating this method (continually) for quite some time. Each powered subwoofer should be equipped with a plate amp that has fully variable phase adjustment to "dial-in" the time delay.
Ex.http://www.parts-express.com/yung-sd100 ... t--301-500
(..you can see the bottom knob on the right hand side of amp provides fully variable phase adjustment, and the knob above it provides a low-pass filter as high as 200 Hz.)
You can also "cheap-out" for a single listener with only 1 subwoofer placed directly behind that person and again making adjustments with the 3 knobs on the amp.
For a single listener however, the best method is a stereo (2-channel) dipole subwoofers placed in the nearfield (less than 2 feet away) from the listener's head - and ironically that starts becoming more like headphone.