Acoustic treatment


I need some advice on how to proceed with acoustic treatment in my listening room.  Setup is Wharfedale Jade 3, Cambridge CXA-81, Bluesound Node 2i, SVS sub.  Stands are damped with pea gravel and sit on needles on metal disks.  Speakers sit on dense foam isolation pads.  They are 30" from the front wall and 40" from the side wall.  Room is about 15x13x8.  On certain music (Hawaiian slack guitar, some soft piano jazz) I seem to get resonance around the bass/mid crossover at 350 hz, perhaps a little higher.  Otherwise I am very pleased with the sound.  I have acoustic panels on the front wall behind the speakers and two DIY tube traps that I've moved to various locations.  Here is my question:  assuming that the room is the problem, should I look in the direction of absorbtion (i.e., a resonator tuned to the 300-500hz range) or dispersion?  Thanks.
treepmeyer
Call GIK or use their room tool. Pretty simple if you have a simple room. More complex, a call would probably be best. It doesn’t take tons of money to get started. Look at your first reflection points, good place to start, then go from there...
Personally I go for absorption and think the more of it, the better. But others would disagree.
Carpet or rug is a good suggestion. For me, I heard the biggest improvement besides bass traps when I treated the first reflection points on the side walls with diffuser panels. Actually, GIK sells stuff that acts as a combination of diffuser and absorber. 
I have a thick oriental carpet on the floor.  Following geof3's recommendation, I put my tube traps at the side first reflection points with the foil half toward the speakers, thus acting as a diffuser for mid and higher frequencies.  It definitely helped, so as I suspected I have a reflection problem.  Chipping away at the problem, which is part of the fun.
I'm sure that Townshend isolation pods are great products, but before I spend $1300 on a set I'm going to spend a few hundred more on taming the reflections in my room.  Thanks for the good advice.