Since speakers often do not have linear impedance curves, you do often have to try other impedance taps to see which offers the best performance.
'Light loading' can be good for the power tubes but can also introduce more harmonic distortion, which will be interpreted by the ear as 'richness'. This is because if the output transformer is not loaded down enough, it can ring (distort although not due to saturation). So there can be tradeoffs as any extra distortion will obscure some low level detail.
'Light loading' can be good for the power tubes but can also introduce more harmonic distortion, which will be interpreted by the ear as 'richness'. This is because if the output transformer is not loaded down enough, it can ring (distort although not due to saturation). So there can be tradeoffs as any extra distortion will obscure some low level detail.