It all depends on the amp design. Typical class AB amp will suffer slightly more distortions with higher bias (overbias) as it is shown here:
http://bgaudioclub.org/uploads/docs/AudioAmplifiers.pdf (chart on page 189)
and here:
http://www.kelm.ftn.uns.ac.rs/literatura/mi/pdf/AudioPowerAmplifierDesignHandbook.pdf page 107-108.
The reason for that is transonductance/gain increase (gm-doubling) when both transistors operate (class A) versus one transistor only (class B). Increasing this area of double gain slightly increases distortions. It is perhaps possible to compensate gain with signal level but it would require special design.
Another problem is that class AB amps use deeper than class A (often 10x) negative feedback to correct transistors nonlinearities. You just cannot simply overbias class AB amp and expect miracles. It is not sound quality vs. power dissipation tradeoff - it is much more complicated.
http://bgaudioclub.org/uploads/docs/AudioAmplifiers.pdf (chart on page 189)
and here:
http://www.kelm.ftn.uns.ac.rs/literatura/mi/pdf/AudioPowerAmplifierDesignHandbook.pdf page 107-108.
The reason for that is transonductance/gain increase (gm-doubling) when both transistors operate (class A) versus one transistor only (class B). Increasing this area of double gain slightly increases distortions. It is perhaps possible to compensate gain with signal level but it would require special design.
Another problem is that class AB amps use deeper than class A (often 10x) negative feedback to correct transistors nonlinearities. You just cannot simply overbias class AB amp and expect miracles. It is not sound quality vs. power dissipation tradeoff - it is much more complicated.