To condition or not ?

My understanding is that a basic regenerator will provide stability for the electricity supplying the motor. I have one dedicated to the tt.  

Some turntables already have a "conditioner" as part of their drive system. Turntables that generate a signal for the motor to run on would not benefit from a "conditioner" The AC lines frequency is held to very tight standards. Turntables with plain AC motors operate on the lines frequency. A regenerator might improve measured performance slightly, but you would never hear the difference. Turntables like my Sota use a three phase motor and drive it with a phase converter that has adjustable frequency. The computer then controls turntable speed by reading a magnet on the bottom of the platter. You can also tell it what speed you want it to run if you want to adjust pitch. A conditioner is worthless on a turntable like this because it is already doing the conditioning. 

It is much more important to spend money on better speakers or if you really want to blow your mind digital signal processing.

@carlsbad2 What does “reported to” mean?  Because by design, Niagaras do not limit current. Interested to know what would limit the amplifier?  You got links?

Reported by users here.  Of course there could be errors but confirmation bias would likely make the errors in favor of Niagara rather than against them.

 What is your basis for saying that "by design, they do not limit power".  I'm sure every manufacturer would make that claim.

On the SOTA, it IS a magnet but that is one half of the device called a Hall Sensor, used in many vintage DD turntables, like my Kenwood L07D, and by Phoenix Engineering which designed the speed control system used in the SOTA Eclipse. I agree that an AC regenerator would be redundant in the SOTA Eclipse system, because that job is done already by the power supply that is part of the Eclipse. However, if your turntable does not inherently regenerate AC, then an external regenerator might be of some benefit. At the very least, it will shield the other front end equipment from any noise in the form of EMI that might be put back into the AC supply for those other components by the motor itself.

Most TT motors draw less than 25W (which in a 120V system means less than ~0.2A), so I doubt that any conditioner (not a regenerator, but a conditioner that uses filters to remove hash from AC) suitable to work in an audio system would limit current draw by the TT motor. I would not put such a device on an amplifier, however, unless I knew it was rated to deliver a multiple of the steady state current draw of the amplifier.