Need help with impedence match Aesthetix and Pass

Wow, Thanks for taking the time to help me out Al.

I ran both the Aesthetic Calypso and now the Signature with Aleph 2s. Very nice sounding match without doing the math. I have sold the alephs and now have a XA-30.5 matched with the Calypso Signature. To my ears the sound is more textured and natural than w/ a solid state pre.

Unfortunately it is not an ideal match, using either the balanced or unbalanced connections, and depending on how much deep bass extension your speakers provide there will probably be a rolloff of the deep bass that is at least slightly perceptible. There might also be small frequency response irregularities at higher frequencies, although probably not with the balanced connections.

I'm basing that on the input impedances shown in the Aleph 2 manual, which are 10K unbalanced and 25K balanced, and on Stereophile's measurements of the Calypso's output impedance, which for the unbalanced outputs are 2400 ohms at mid and high frequencies and 3150 ohms at 20 Hz, and for the balanced outputs are 112 ohms at mid and high frequencies and 3900 ohms at 20 Hz.

Ideally the amp's input impedance should be at least 10x the preamp's output impedance, at the frequency for which the preamp's output impedance is highest.

Regards,
-- Al