Power conditioner some say yes and some say no.

In my case I have to use one -- one of those old Tice units (badly reviewed sometimes) and the big old "power block" storage device. 

I bought the set simply because my house is wired is at 30A, my power-amp if used at higher volumes caused the lights to dim and if we were also using the air conditioner and/or washing machine we'd trip the breakers. The conditioner/power storage set eliminated the problem.

I thought I heard some reduced dynamics when I first plugged them in, but I had just gotten through reading someone who said the Tice units "stangled" the sound of his system. I don't hear it now. I don't know if my initial impression was biased from his comments, I've gotten used it or what. I will say I enjoy the hell out of my system and until I move to a place with more robust wiring, I'm stuck where I am and it's not a bad place at all -- I like being able to "open it up" without fretting about the breakers.

I should add I'm kind of a 'budget' audiophile -- what I have is what I could afford.

Again, I’m agreeing with jason bourne 52. I suspect power conditioners are a cottage industry exploiting the placebo effect. Having practiced medicine for 30+ years prior to retirement, I am familiar with this effect. It is relatively easy to install a power conditioner, just plug it in. But to make a meaningful improvement in,say an amplifier’s, performance, one must disassemble the device and modify the power supply, usually by installing increased capacitance.

A new descent Furman can be had for 125-220$ with lights, and good over all over current protection. 
 We have horrible power here, as mentioned the wall voltage, goes up, down, 116 up to almost 123, the Furman shuts everything down in a millisecond when voltage gets above a specific voltage. 
 Can be a pain in the butt at times, but I feel safe knowing my audio is protected. 

I bought an Audience AR6 three houses ago and it helped a lot with noise.  Each time I’ve moved I have just plugged it back in.  Been here two years and never checked.  Maybe I’ll unplug it for a time and see if anything gets worse.

JD