I know PS Audio (I believe) offered power regenerators. Very large heavy units. I tried a unit several years ago, no longer in production and it was nice. However, my current power conditioner made my system sound better. I'm sure the current PS Audio units are much better now.
Again, most utilities provide voltage that fluctuates depending on what loads come on and off on the system. (before anyone argues with me, I am, along with my analog/digital Engineering degrees and background, a state certified Power Engineer working for a local utility). So, for example, with stable loading, the system provides 120 Volts at 60 cycles per second. Now turn on large loads/motors, etc. That voltage will drop for a very short time until the system generation can catch up. Same is true with frequency. If large loads suddenly go away, the voltage may increase along with the frequency.
This happens on the system all day at all hours. more stable at late hours. reliable utilities have generation on stand by and rolling to provide this much needed system stability. So, even if a large generator is tripped off-line due to a fault, the system will remain relatively stable because of the other generation.
If you don't have a speed controller on your turn table, or if it isn't integral with your turn table, if you place a stroboscope on the turn table with a regular incandescent light, you can see if the speed is accurate. depending on the time of day and system loading, it is not. Hence the need for a speed controller.
But, there can be lots of noise on the power lines, which will make their way into your audio system. Most equipment's power supplies have within the power supply filtering that will try to remove noise. One thing power conditioners will help with is lowering the noise floor significantly.
To see if it is needed, it is simply a matter of getting your hands on some decent power conditioners and doing an A/B comparison. With power conditioning and without it. Or compare various conditioners.
I can't speak for the really expensive heavy duty power conditioners that provide for large amps to be plugged in also. Most choke the power to the point where amps don't sound good plugged into a conditioner. However, as I mentioned, there are some that work quite well that allow for power amps to be plugged into them also. They are really expensive, large and heavy. But, they do work.
So, I can't say as some said earlier that power conditioners either work or don't . It depends on what is going on with your system and the voltage from the utility. is it clean and stable? if not, then yes, you definitely need a conditioner.
It is funny. You think your system is great until you do an A/B in-home test with another piece and all of a sudden the background noise is way less or you hear things you never heard before in your music. That is the problem. There is always something better than what you have or something that can help.
But, listen for your self.
enjoy