It is hard for class G amp to compete with class D amp because class D amp has atypical efficiency of 85-90%, and even the best class G amp can’t match that. But the class D are also more complex, and with high frequency switching, the PCB layout is critical. Even with the availability of the best circuit, there will will be some emitted RF noise. Most class D also have a frequency response that is only flat for one load impedance.
With the potential of RF interference problem, the class D can be avoided by some. Sure the class can deliver excellent fidelity and very little heat at high power levels, but that doesn’t mean they are accepted as the most ideal amp.
Almost all class D amp use surface mount devices and specialized IC. When the parts become obsolete, the amp should be replaced, because it is useless to repair them.
