[Amps] Effects of load Z mismatch?

[Jim Kearman]

I'm aware that properly matching the tube to the pi network results in best efficiency and, presumably, less distortion. But to what extent? 

Let's say the correct ZL is 1500 ohms, and your pi net actually offers 1800 ohms. What impact does this 1.2 mismatch have on overall efficiency and distortion? 

I'm wondering how much time it's worth spending trying to empirically determine the best LC ratios. 

Thanks.

73,

Jim, KR1S