The maximum voltage output of the amp is 25 volts and it is designed to deal with difficult/reactive loads (it will operate through a dead short). The speakers clamp the inputs at 40 volts. It seems to work really well with them, and will play quite loudly with no adverse distortion. The manual for the ESL-63s says that with amps over 35 volts you should be careful with the volume and that a steady 10 volts should not be fed to the speakers for prolonged periods, and that an amp with voltage output of between 20 and 30 volts is ideal. So its seems kind of right in the ballpark for what they should require, and that an amp that puts out more than 30v is wasted on them. Or in their words "there is no benefit to be gained". I'm glad you asked this, as it made me look up the voltage rating of the Aleph and the requirements in the ESL-63 manual, out of my own curiosity. Seems my ears were right on the mark with what was sounding good here.
I haven't found typical wattage-only ratings to be of much help when figuring out what plays well with the Quads. The 15wpc Leben must have low voltage output as it got barely a whisper out of them.
I haven't found typical wattage-only ratings to be of much help when figuring out what plays well with the Quads. The 15wpc Leben must have low voltage output as it got barely a whisper out of them.
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