David Thiel has addressed the concerns regarding audio quality over on Pinside:
“I’m concerned about first PF experiences that refer to 'static' in the sound. I've had a pre-production PF for more than a year and have turned it up (so that the floor shakes). There is no 'static'.
Just to be sure, go into tests. There is a sound test that plays "this is the cabinet speaker", "this is the backbox speaker". Make sure that these audio clips are coming out of the correct driver. Sound will be 'not good' if the speakers are not connected correctly.
At shows or in loud arcades where there is the potential of a 'volume war' all the pins lose.
In a private environment I am confident that the PF sound system is competitive with the best sound systems I work on. CGC uses very good speakers and the industry standard TI class D amp. It is loud and punchy. There is an operator adjustment for the relative contribution of the cabinet speaker. This can make provide more punch if PF is operated on a concrete floor.
Except at the loudest possible volume settings PF should be distortion free and loud. If it isn't, submit a ticket as this is an issue to be fixed.
The CGC system is digital from the CPU to the amplifier. No hum inducted through analog cables. A side effect of this is that there is no analog out which makes getting the audio for Twitch streams challenging. Karl has done a great job at capturing the audio for his '666' challenge, I've enjoyed watching it.
Since the signal going to the cabinet speaker has been processed for max low end, I'm not sure what the effect of an external subwoofer would be. It should be used judiciously. If you like bass, then so be it, it's your machine.
Finally, there was no mandate to sound 'cheesy' like a vintage pin. This is 48 khz, uncompressed audio rendered with full range-bandwidth. Music was 'enhanced' for more kickass bass than existed in the original 'mono' recordings (Jungle Boogie was stereo). Everything was tuned to sound as good as possible with the pin audio system. If that is not what you are hearing, then something is wrong.”