power amp/pre amp input and output impedence question

As long as you are north of 10:1 you're good. The only issue you might run into with amps with a very high input impedance is you might want to keep the capacitance down with your interconnect cables so as to maintain high frequency bandwidth.

@kgveteran Yup! Sometimes the output impedance of some preamps isn't all that low (particularly tube preamps) even though on the right setup it can sound pretty nice. In some cases the manufacturer might not have even measured it.

We don't specify out output impedances either, but we **do** spec that they can drive a 600 ohm load and that the output impedance is flat with respect to frequency.

what effect can be expected from a miss match.

What does an output impedence of 1.2k ohm say to the expert......

If the ratio is less than 10:1 you might have less headroom before the preamp makes distortion. There would also be more overall distortion so less detail and probably harsher sound.
An output impedance of 1.2K ohms isn't bad. You can drive amps with 20K or higher input impedance no worries. The thing to look at is the output impedance at 20Hz. Many preamps have acceptable output impedance at 1KHz but at only 20Hz their impedance can be quite a bit higher. If at this frequency its less than the 10:1 rule of thumb you might experience less impact in the bass.

The rule of thumb is the input impedance should be at least 10 times the output impedance!

'Input impedance' referring to the amp, 'output impedance' referring to the preamp.