Your One Bullet Point Solution; Electrical Upgrade

Ok. Here it goes. Do a 200 amp new main panel by Siemens or cutler hammer with copper busses. Your electrician should follow codes for ground rod install. Then attach a whole house surge protector to the main panel. Eaton is fine. Then for your audio, get a dedicated 20 amp outlet with an audioquest 20 amp nrg audio outlet. I’ve been a builder for 30 yrs and I just completed my 20th home. You will get rid of your sub panel since you will have plenty of breaker slots for your home. Have fun and good luck. 

Btw, this will not be cheap. Not sure where you’re located but in Chicago it at least 3k. 

I would assume you are doing this undertaking to make sure that power is not a limiting factor in sound quality.  Before you spend all these money, lets look at what and why.  Given that otherwise power quality is acceptable (no EMI, etc.), the main limiting factor from AC power would be too high of output impedance, i.e. sagging even for a shortest time under changing load.  A valid concern, since this introduces nonlinearity, intermodulation distortion, and reduction of dynamic range.  But the current rating of your incoming power and details of your distribution panel are not the main bottleneck in the entire power budget.  The in-wall wiring and all the old twist-on connections are.  Unless you recently upgraded your wiring and know exactly what it is, my guess is that likely you have AWG12 solid wire connection at best, or even thinner wire.  NEMA requires AWG14 for 15A branches and AWG12 for 20A branches  With long runs and likely several twist-on connections with possible oxidized copper you may not see much actual difference once you are done with the upgrade you've mentioned.    
If the situation with wiring is what I described, you would better off using a good quality power conditioner that would compensate for the deficiencies of old wiring.  To toot my own horn, my company makes EMI filters for industrial applications with very low output impedance that compensates for some problems in wiring, as well it gets rid of EMI just about completely:  https://www.onfilter.com/ac-power-line-emi-filters

However many slots you put in, you will want more! I like Siemens. I have a small sub panel for my lab, a middle sub panel for kitchen, HT, and music room, and a very large main panel. I still have a few slots left over.

Never lost a Siemens breaker in 20 years.

Doug, don’t forget a meter socket SPD. This is the first line of defense in terms of surge protection. Depending of where you live, you might have to ask the power company to install it for you and they will charge you a small monthly fee. It goes outside, right behind the meter. Most people miss that part. Good luck. N.B. The equipment and its maintenance is handled strictly by the power company.