I currently don't have any power conditioner/surge protection and live in an area where a spike or surge happens, on average, once every 2-3 months. I have used Richard Grey,Audio Prism,PS Audio Ultimate Outlet and VansEvers.After several spikes with my vintage tube mono block amps on and my Naim cd player /power supply on ,I 've found that they could tolerate the spikes without any protection.
I've found that ALL these devices have altered the sound of my system ,especially the amps. While I could hear some improvement in 1 or 2 areas ,they also had a negative effect .Most notable was the PS Audio ultimate Outlet which greatly expanded my soundstage BUT at the expense of clarity in the midrange.
During the big blackout this past summer I had my system on and wasn't home for 2 days .When I finally was able to get back home all was well.If it could handle that load then why bother to spend hundreds of dollars on a piece of equipment that will alter the sound in a measurable way.It's adding another varaible to the mix which,sooner or later, will be sold for yet another power conditioner with the promise of audio nirvana.I'd rather spend the $ on upgrading tubes,or buying music or inexpensive tweaking.
The precaution I do take is unplugging during a thunderstorm or when I'm on vacation.JMHO