If you placed the absorbers before moving the speakers, the absorbers are no longer in the correct places to do their job. They need to absorb first reflections and standing wave energy in corners, which have all changed since the speakers were moved. You can use a mirror to see where these reflections are occurring- sit in the main position and have someone move a mirror along the wall- when you can see the reflection of your speakers, put a piece of painter's tape on the wall. You'll need to do this for each front speaker- a strong reflection from the left speaker can cause phantom sounds to seem like they're coming from outside of the right speaker and vise-versa. Reflections occur on the ceiling and floor, too- if these are bare, the reflections need to be addressed- a dug can be put on the floor but some kind of panel or covering does need to go on the ceiling.
Guilford of Maine is the "go-to", but not the only fabric that can be used, by any means. Most of theirs look too commercial for residential applications- if you can easily see through it, the sound will pass through it to the absorptive material.
You really need to find which frequencies are still accentuated- the panels will absorb more or less at specific frequencies, based on the material type and thickness and if you look at the specs for ANY construction, you'll see mention of ASTM, NRC, STC, etc- ASTM is 'American Society for testing and Materials', NRC is 'Noise Reduction Coefficient' and STC is 'Sound Transmission Coefficient'. These are internationally used for construction and manufacturing.
NRC indicates absorption ability and it's shown in graphs. STC is the amount of sound that can pass through a material without attenuation- you need to find the reflective points before placing the panels, measure the response and figure out how much material is needed- evenly placing panels isn't the way to go about this- it needs to go where it will be most effective and if more absorption at specific frequencies is needed, it may be necessary to use a thicker panel. Once the locations have been found, start by placing the panels for the first reflections from the L & R speakers and measure the response (or listen, but measuring makes it easier to see the changes). Next, place the panels for the first reflections from the speaker on the opposite side- if you can't, you can't but if you can put a chair between the speaker and that spot, do it- the result will be similar.
Once this has been done, live with it for a while and if it works without someone telling you that it needs to go, great!
Foam is useful, but not as effective as Roxul and Owens-Corning 701/703 panels or batts.
