I use the Bass Busters in each cornor behind the speakers. In my case, the improvement was worth the cost. Much better definition in the low bass, and more stable and focused imaging. I also use the RPG Pro Foam for wall treatment. I have not tried the ASC products, but they offer a broader range of bass trap options than Echo Busters, which are only available in quarter rounds.
The Bass Busters don't look like much in the pictures you see in thier ads, but they are quite heavy, and well built. I recently stumbled on a tweak for them. I had a set of Vibra Pods that were sitting un-used for a long time, because I never liked what they did under my components. I was going to throw them out, but just for grins I placed them under the Bass Busters. This seemed to improve thier effectiveness, but I have no idea why. Anyway, if you have not tried room treatment you should give either the Echo Busters or ACS a try. I think you will find the improvement they make far better than any interconnect or power cord upgrade that would be compairable in cost.