It may be worth getting an electrician out to do an assessment if you feel the issue is significant. They can relocate circuits to rebalance and minimize the impact of your A/C kicking on and diagnose other issues, such as worn breakers.
In my case, I had an electrician come out and upgrade my panel. I still have a slight hum on the line I haven't been able to completely eliminate so using a Furman IT-Reference-20i with excellent results (so much so I'm looking at upgrading to an Audioquest 7000 in the future). The Furman's balanced outlets have a noticeable improvement on my pre and DAC and plugging my amp and other high current devices into the high amperage outlets doesn't have any negative effects.
I have a SurgeX SEQ and had a similar experience with it affecting my highs. I also have a Furman SPR-20i and was able to speak with its designer, Garth Powell, which convinced me its unnecessary in a residential setting so have since just been running the IT-Reference-20i alone and haven't noticed the negative affects of summer power.