Subwoofer power conditioner

You always want a power conditioner and surge protector.  Always.  One with good EMI filtering is important.  Look for something that will handle an 8000A surge or more and suppress EMI, sometimes called RFI, down at least 30 dB out to 30 MHz or more.  Most EMI problems are solved when suppression is down 30 to 40 dB across the board but really 60 dB is far better.  The problem is paying for that added 20 to 30 dB of suppression.  That is my recommended minimum.  If you want more, then look at the regenerative units, but they get very pricey. 

I plug my RELs into an Everest.  Supposedly the Everest has six and Denali three independent circuits capable of momentary 30 amp current to power amps.

I live in SC, and in California before then (PG&E!).  I would not plug anything directly into the wall outside of major appliances and lamps. The threat of damage due to surges is real.  I recently lost a Macbook which I had forgotten was left on the charger overnight during a lightning storm.

Now, should you buy a very expensive "power conditioner" that isn't even UL rated as a surge protector?  Not as far as I'm concerned. :)

Here's my recommendations right now:

On a related note, I just went down a long thread about amplifiers elsewhere and I found this online review for an amp of brand X.  The guy, hilariously IMHO, goes on at length about how terrible Krell amplifiers were because he bought 2 different models and they each failed in a month.  What he misses, based on his own description, is that both of his amps were taken out by electrical surges. 

Don't be that guy.