I owned Spectra 11s for 20 plus years and upgraded them to Spectra 1100. Through much experimentation, I finally found the perfect woofers for them: Peerless sourced, NHT SW4 sandwich cone drivers. I originally only used my 10 and 12" subs with this setup to compare, and the bass of the 8" is plenty for normal yet loud listening; however, since the panels are a line source and the subs are a point source, the bass diminishes in volume compared to the rest of the music the further you are from the speakers. From 20-30 feet away, the matching Peerless NHT SW2SI subs bring this bass back.

First, the woofers in the Spectra 11 are terrible. I believe boomy woofers were used to detract potential buyers from their expectation of a weak bass in panel speakers. The 1100 woofers are tighter, but the Peerless 8 inchers are perfect. The NHT SW2, SW2P, SW2Pi, and SW2Si cabinets are the same, but only the Peerless sandwich cone in the SW2Si is a serious audiophile component. A little wood removal is needed on all but the Si cabinet to clear the connectors on the much larger magnet of the Si.

I had Magnapans before and really hear a difference in quickness of the upper reaches of the electrostatics vs. any other type of planar speaker.

The nicest thing about any panel speaker is its coherance of sound, usually attributed to the lack of a crossover network. The worst part of the sound in the extreme highs, or lack of. Martin Logan has added tweeters to their range of electrostatics.They are a selfish person's speaker with a definate sweet spot. No sharing with other listeners!

I really believe that my upgraded Acoustst are an excellent speaker, but the loss of detail that worsens the higher the frequency. For the 450 I sold mine for, there is no better speaker, but change the woofers.