I was also in the hunt for improved bass SQ. But separately, I wanted to change out three plugs on power chords while shortening their length, so I checked around the forums and selected plugs from Cardas, Neotec and Furutech, all "moderately" priced (for audio stuff).
Result: noticeably improved bass, deeper, clearer notes and less general bass thump. Sometimes, small things just work out.
Result: noticeably improved bass, deeper, clearer notes and less general bass thump. Sometimes, small things just work out.