I've got the Summertime Blues. Power conditioner necessary?

Is you system worth protecting?  You need to be using some power plan and keep upgrading as you can.  

Usually not worth the money or effort.

You might not need to spend a lot to solve this issue. I was having some noise issues as well. And sometimes crackles coming thru the speakers during summer storms that happened often where I live. On a recommendation from another forum I bought a Furman PST-8D for $150 US. Problem solved and the sound of my system improved, which was unexpected. This box is impressively built. I'm sure the more expensive Furman units are better and perhaps there are amazing improvements beyond that available from other solutions. But I'm not spending my money on those things- just yet. Now that my power problem is solved I'm upgrading some components with money I was going to spend on a different power solution. 

i am using a furman PL-8C using the 2 prong adaptor into the wall. generally, we have good hyrdo-e power and it does not seem noisy, but the PL-8C gives me some modicum of protection and i have a black noise level......
no air con ... but lotsa fans! the actual wiring in my hovel is a bit scary....
i got a lo-fi system but it is the best i ever had...

I agree that one of the better Furman's will help the situation by cleaning up the electrical signal and providing steady voltage. I have a Furman Elite and it works well. Next to it sits an Audioquest 7000 which works very well but very expensive.  In your case the Furman is probably the better choice. Talk to Crutchfield. They sell Furmans and know what they are talking about.