Regarding electrostatics and Class D amplifiers, my Acoustat Spectra 1100s are rather inefficient and dip to slightly less than 2 ohms at very high frequencies. I have had no trouble driving them at "normal" levels (i.e. Dolby Atmos reference levels with real-world material) with Class D Aiyma A07s. I've run them full range and bi-amped with external DSP for crossovers, EQ, etc. I currently bi-amp them with Class D Fosi V3s running on 48VDC/10A power supplies with zero issues. (Note that in the Spectra 1100, a sealed 8" woofer operates between 35Hz and 250Hz. The electrostatic panel is crossed over at 250Hz electrically at 6dB/octave, when operated in stock, full range mode. In biamp operation I use 24dB/octave slopes at 250Hz.)