Modwright LS 36.5 or BAT VK-51SE

Since the output impedance spec of the Dude is not provided, it seems to be a situation where you'd have to hear the preamp in your system to decide if it matches or not. You'd want to be listening for rolled-off highs. I don't know what a resistor pull-down XLR is.

The BAT VK-51SE was tested by Stereophile, and the output impedance was measured at 410 ohms (200 ohms spec'd by BAT), and rising to 4700 ohms at 20K.

Grant, I think you meant to say 20Hz, not 20K, and that what should be listened for is rolled off lows, not highs.

I don't know what a resistor pull-down xlr is either.

The posts by Atmasphere starting here provide some insight into the output impedance of the Dude. It sounds like a major contributor to its output impedance is the volume control and its setting (he indicates that the control is located at the output), with the output coupling capacitor perhaps being no more than a secondary factor.

Since the volume control is essentially resistive, rather than capacitive, its contribution to output impedance would be pretty much constant with frequency. So high output impedance would be much less of a concern than in the more common situation where it is due primarily to the output coupling capacitor, which would cause the output impedance to be much higher at very low frequencies than at higher frequencies. It is the DIFFERENCE in output impedance between those frequencies that causes low frequency rolloff when output impedance is too high relative to power amp input impedance.

Best regards,
-- Al

I should add to my previous post that high output impedance that is primarily resistive, and is therefore high at high frequencies as well as low frequencies, can result in upper treble rolloff due to its interaction with cable capacitance. But that is easily avoided by using low capacitance cables and/or avoiding long cable lengths, and is unrelated to which power amp is used.

Best regards,
-- Al