Surge protectors--how many $ make sense?

You may want to consider entire house surge protection instead. There are commercial/industrial solutions like from Siemens with $75K insurance for 10 years. These are REAL things that WILL protect (Monster never protected mine, it is all lies). And they do not cost $$$ more like few hundred dollars. Talk to a professional electrician.

https://www.siemens.com/us/en/products/energy/low-voltage/surge-protection-devices/residential-surge.html

I am sorry, but I will never again buy any "audiophile" or "home equipment" surge protection. I rather get equipment that is used to protect really expensive professional stuff out there backed with money guarantees. I guarantee you, big recording studio is not using any Monster or anything "audiophile".

A system at the level of yours deserves a bit more than a plain old surge protector. But definitely invest in a whole house unit, they are relatively cheap. For your system, do some research and invest in an audiophile level power system, either passive or active. I have tried the passive route with okay results, but now have dived down the regeneration rabbit hole with PS Audio with very good results. 

Surge protection is a good thing for all the appliances in your house. If your utility allows it, a Type 1 protector installed in your meter panel is an excellent first line of defense. My electric utility doesn't allow use of Type 1 protectors, so I settled on the next best thing, which is a Type 2 installed in the electric service panel.

I have power conditioning installed ahead of my audio components, but I don't think of those units as surge protectors.

@cleeds Power conditioners generally provide a level of protection against surges.  Now the power condition could end up being sacrificial, which will bother some because of the price, but it is really hard to protect everything.  I will never put a current limiting device on my amp.

Jerry

If you are looking for true surge protection, I suspect the SurgeX products would fit the bill.  Of course, there are those that would never accept such a "non-audiophile" product.

I suspect on many systems, current limiting would not be an issue and surge protection would far exceed what many "power conditioners" afford.

I use a whole house type II (at the main service panel) from Siemens plus on the main system, a surge board in the iso transformer that protects the outputs- 4 gauge to a sub panel that feeds 10 gauge dedicated lines. For most appliances, computers and my vintage system, I use point of use surge protectors. I keep the antique Quad Loudspeakers in the vintage system on constant charge using a Zero Surge.

"Whole house" may not be sufficient (some surges are within the household system and the "whole house" will not address these); also, a lot of the conditioner/surge protectors have a sound. That’s where you have to experiment through try before you buy or buy with the right to return with minimal penalty. The Siemens FS 140 is overbuilt, but still uses MOVs and has gone up in price; I used an Eaton before that. There is an "audiophile" whole house by Environmental Potentials that is now about twice the price of the Siemens, have not tried that unit. There are also more industrial/commercial units that can be even more spendy.

My go-to on electrical systems is @Jea48. Others here are also knowledgeable.