I have a number of thoughts for the OP:
I have not heard a power conditioner on an amp that i liked, compared to going straight in. (I haven’t heard the Audience, which seems to have very strong support from high end community, but don’t know if that is mainly for front end/smaller components, not power amps).
Surge protection is, I think, a little deceptive in a couple respects: first, the big worry is lightening strikes. If your house or your transformer gets hit, I suspect no black box, whole house surge protector or other device is going to save you from damage.
More likely are voltage surges-- that EP 2050 would certainly be one of the nicer whole house units on the market. According to Chris’ description on the link posted above, it does use MOVs, but only for the big hits; otherwise, the MOVs are not in the circuit.
Trying to be realistic about this, maybe one of our more astute electrician types, like @Jea48, or electronics gurus, like @almarg, can weigh in on the peak power of dangerous surges. The EP is rated at 12kVa, but the Eaton I have (it uses MOVs with a set of lights to tell you when to call the electrician and replace the thing) is more like 80kVA peaks per mode. Do you need that much?
I don’t rely solely on whole house. For example, I have a pair of electrostatic speakers that must stay plugged in all the time. For those, I use a box made by ZeroSurge, in Frenchtown, N.J. Uses no MOVs. Well made and I believe they hold the patent and license their technology to several other competitors. Basically plug into a wall outlet at point of use. Will it color or limit the sound of your amps? I don’t know. I never tried it on my amps. In my application, it is keeping the panels charged with voltage, so even if it were colored to some degree, I don’t think it would matter much. It certainly isn’t choking current in that application.
My main system goes through some additional, fairly elaborate electrical work, separate subpanel, to 10kVA isolation transformer with its own surge protection board (40 or 50kVa per mode) plus some EMI filtering, to dedicated lines for the hi-fi. If I was really anal about it, I could theoretically put point of use surge protection on some of the components, too. (All my record cleaning gear goes through a 4 outlet Tripplites; ditto some other accessories, like the record flattener. But none of that connects directly to the system).
My practical answer is simply to pull power in a bad storm.
The other observation- and those with more electrical knowledge can correct me if wrong, but:
-a surge protector of any type or size doesn’t protect against power dips. Those can be hazardous to your gear as well.
-some surges can result not from lightening or other acts of God or the power company, but simply as a result of what is going on within your household electrical system. I’m not sure how fully dedicated lines isolate that since they still share a common ground with the rest of the house, but it may give you some additional reasons to consider the whole house approach, plus something else.
