The diodes have low current and should match the low current of the base-emitter diodes of the output transistors. I would use little 1N914 or 1N4148 diodes but they are difficult to fasten to the heatsink (to sense the temperature) of the output transistors.
Power diodes will probably cause crossover distortion because they have a lower voltage drop at the low current the diodes pass.
Power diodes will probably cause crossover distortion because they have a lower voltage drop at the low current the diodes pass.