Pass XA30.5 enough power for Wilson Sophia 2?

A lot of (most perhaps) preamps have output impedance that is too high for the Pass.

Some tube preamps =may= be too high, but I'd be surprised if any solid state units are. I think your statement is a distortion.

A lot of (most perhaps) preamps have output impedance that is too high for the Pass.
Madfloyd (Threads | Answers | This Thread)

That is just flat out wrong. The low input impedance of the XA-.5 series is 20k Ohms (single ended). If one uses the 10:1 rule, a preamp's *highest* output impedance can rise to 2000 ohms and still match well. There are very few preamps that have output impedances that rise to 2000 ohms (although there are some). If one is running an XA-.5 series Pass amp in balanced mode, then the input impedance is 30k ohms, and the 10:1 rule would allow for a preamp's *highest* output impedance to rise to 3000 ohms and still mate properly.

With my XA-60.5 amps, I successfully used the following preamps (followed by their respective balanced output impedance):
Lamm L2 Reference - 130 ohms
Lamm LL2 Deluxe - 250 ohms
Atma-Sphere MP1 - 30 ohms
SMc Audio VRE-1 - 250 ohms
ARC Ref 3 - 600 ohms

What specifically is the model of your preamp, and what is the output impedance?

That is quite a line-up of great preamps. I did once use the Audible Illusions 3A with the Aleph 3, which I think was 10kohm input impedance, and the AI3 was realtively high outut impedance, and I did not notice any problem driving the load. I would say that 95% of preamps should be OK with the Pass, it is an issue, but is not likely a problem with most, if not all, preamps - certainly not ideal for those seeking a passive path to preamplication.

My understanding is that a 600 ohms preamp impedance output (like the Ref 3) requires an amp with 60k input impedance.

06-12-10: Madfloyd
My understanding is that a 600 ohms preamp impedance output (like the Ref 3) requires an amp with 60k input impedance.

600:60,000 is a ratio of 1:100.

Your understanding is erroneous.