Anyone have experience running them with Quad electrostatics, which go
down to 2 ohms in the high frequencies. Considering for a pair of
stacked quads.
Most Class D amps behave as voltage sources, which is to say that they can double power as the impedance is cut in half.
This does not work in your favor in the case of ESLs, the reason being that the typical ESL has an impedance curve that varies by about 10:1 from the bass to about 20KHz. In addition, the impedance curve is not based on a driver in a box as you know.
When the impedance curve **is** based on a driver in a box, the impedance curve is also a map of the efficiency of the speaker; so for example the resonant peak of the driver in the box will be a peak in the impedance curve.
ESLs have their impedance curve based on a capacitor so its not a map of the efficiency of the speaker. IOW, the speaker has the same efficiency from the bass all the way to 20KHz or wherever it rolls off.
We all know that solid state amps and also class D amps can often double power as impedance is cut in half. Think about that happening over a 10:1 range- the amp will be making about 8x more power than it should at high frequencies. This is why solid state amps often sound bright on ESLs.
