Are my amp and preamp mismatched?

Its a 40:1 ratio which should be fine. 

I have read in another post that the Pass X-250 is best paired with a preamp with an output impedance less than 300....so I was second guessing my pairing. Thanks!

"The Pass has an Input Impedance of 22k ohms balanced"

This impedance rating is for a balanced signal and I believe your preamp is single ended. The input spec of the Pass for SE is 11 kOhms.
The calculation for impedance matching is 20. IMO, this would be the minimum needed for your preamp to drive the amp with no loss of dynamics at all frequencies. However, peaks and transients in the music have to be considered, but they are of such a short duration that clipping by the amp may not occur.
  The reason I use the impedance calculation result of 20 rather than 10 is to take into account transients and the impedance of low frequencies.

The X-250 is not a fully balanced differential amp, so it accepts a SE input and converts it to a balanced signal. 

So how does it sound? Ever notice any clipping? I'll bet the two components work well together.

Thank you for the reply. No clipping yet. The sound is solid, especially the bass. The music definitely has more presence than my previous tube amps.

How do you think using a balanced preamp would change things?