I recently got some Thin Fat Dots (dBneutralizer discs) to put between my electrostatic supertweeter modules and my main speakers. I was mainly hoping to sweeten and clean up the high-treble output of the electrostats (6 kHz and up) and the Dots not only succeeded in doing that, BUT I also noticed a big improvement in BASS articulation, pitch and extension. It was really remarkable!
At first I felt there was a downside in terms of a rounding-off of leading-edge transients, especially on high piano notes. However, the cleanness of the highs allowed me to raise the output level of the tweeters a couple of dB (they are adjustable) and this help bring the transients back. Putting Herbie's Spade Lug Washers on my speaker cables at the amps and the tweeters also helped restore the right level of transient speed. Nice going, Steve!