AC/Generac Transfer Switch

I cannot speak for Generac but I have a whole house Kohler unit and when it is running I have learned not to even bother to listen to my stereo due to the amount of very noticeable background noise. The voltage is spot on but the noise coming through my normally dead quiet system makes listening intolerable to me.

I also had the electrician pull a separate earth ground specifically for the 2 circuits not tied to the main panel.

That makes me question your electrician’s qualifications...

As for your question.

Feed the power for the audio room audio equipment ahead of the Generac ATS

There are a few methods for doing this that will meet the 2020 NEC code.

Texas has adopted the 2020 NEC, (National Electrical Code).

Worth checking;

2020 NEC:

230.71 (B)

230.85 Emergency Disconnects.

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@lwin When you speak of this noise, is it safe to assume that it's electrical noise (hums, buzzes, etc) that you're hearing through your audio system itself, and not mechanical generator noise that you're hearing through walls or windows (mechanical noise that's interfering and mixing with your ability to cleanly hear your audio system)? 

All switches put noise on the line when they break contact. The transfer switch won't be a problem when closed against utility power.

You cannot use a subpanel at the service anymore if your local building department uses the 2020 NEC. That panel will have to be a service entrance rated panel (load center) with a main breaker disconnect or a switch in a separate enclosure ahead of the panel if it's not a load center. 

I would say talk with your electrician, but if he installed more than one ground at your house I doubt he's got a license.

I have a 200 amp service and a 100 sub panel and they both share the same ground. Did your electrician say why you needed a second one?  Did he charge you for the second one?

Several of us are very curious.