Right, there is little to no current drain for an ESL bias supply, just high voltage. Power cords make no difference. The bias supply can actually drift up to 10% and you probably would never hear it. I can decrease the power by 500 volts and you can not hear a thing.
KLH 9's like Quads are very intimate speakers in spite of their size. They sound best close in and close together. The 9's are certainly more reliable. But they are touchy speakers to set up right as the high frequency balance evolves as you go off axis or change height. You set them to sound right at the listening position which is the best you can do.
Acoustats were the first ESLs that had reasonable dispersion and were truly indestructible. As they evolved into the 8 foot tall "plus" models things got really serious. Now you have full range line sources capable of projecting more sound into a room with much less distortion than any dynamic loudspeaker that was not itself a line source. Sound Labs further refined the ESL giving it a perfectly even dispersion pattern over 45 degrees and even more detailed imaging.
Having used ESLs with occasional interludes with planar magnetic and ribbon speakers since 1978, I have return permanently to ESLs. IMHO nothing trumps a line source ESL. It is the loudspeaker with which you are most likely to achieve the absolute sound. As JGH said back in the 60's with the Model 9 you don't listen to the loudspeaker. You listen through it. I think that applies to all decent full range ESLs. I close my eyes and I don't hear loudspeakers any more., they disappear.
