SLAA898 September 2022 TAS3251 , TPA3255
Resistance must be delicately matched in the constant voltage system. In general, it is better to have a larger equivalent resistance for both sides of the transformer, as long as the power is large enough.
According to Equation 42, for a constant power P, the current goes lower as resistance R gets higher, which helps to make the transformer work far below the saturation limit. For the amplifier, a higher R also helps to increase the percentage of efficient power. The performance (THD+N) improvement with a higher R can also be achieved (shown in Figure 3-8 and Figure 4-3).