Here is a quote from the Stereophile measurements section of a review of the Calypso:
"The Calypso’s output impedance was very different from the balanced and unbalanced outputs, suggesting that the former have an additional buffer stage (though no suitable solid-state devices can be seen on each channel’s circuit board). The balanced output impedance was 112 ohms at 1kHz and above, this increasing to 3900 ohms at 20Hz due to the finite physical size of the output coupling capacitors. The unbalanced output impedance was a high 2400 ohms at midrange and high frequencies, rising slightly to 3150 ohms at 20Hz. In unbalanced mode, the Calypso will need to be used with a power amplifier offering an input impedance of at least 30k ohms if the bass is not to sound lean."
Read more at http://www.stereophile.com/content/aesthetix-saturn-calypso-line-preamplifier-measurements#6gvK06VGs...
There is often a discrepancy between the nominal spec published by the manufacturer and the measured spec found in Sterophile, but this is a pretty large one.
Here is the input impedance measurement for the XA-30.5 also from a Stereophile review:
"The XA30.5’s voltage gain into 8 ohms was 26.65dB from both balanced and unbalanced inputs, and both sets of inputs reserved absolute polarity; ie, were non-inverting. (The XLR jacks are wired with pin 2 hot.) The input impedance of the balanced XLR jacks was 29k ohms, close to the specified 30k ohms; the input impedance of the single-ended RCA jacks was higher than specified, at 20k ohms. Both figures were constant across the audioband."
Read more at http://www.stereophile.com/content/pass-labs-xa305-power-amplifier-measurements#9UQSdwSd6MpXya1G.99&...
I would talk to the people at Pass and Aesthetix before buying the Calypso. Both companies are good about helping owners, new or used.