You may get more mileage by getting a cheap outlet tester and going through the house to see where you may have issues like no ground, reverse polarity etc. These are very, very easy fixes and will likely make more impact on cleaning up noisy lines.
I know it definitely helped in my house. Power conditioners are helpful too but IMO, they usually help more with issues stemming from amps, pedals etc.
It may even make sense to have an electrician do a health-check on your house power. Things like rebalancing your breaker box, replacing bad breakers etc. It's not expensive either. Especially if you know an electrician.
Good luck.
Dave