Line conditioner for turntable,

PS Audio power plants are, at least at face value, capable of speed control.

Ohala is correct in that the PS Audios can be used to provide 33 (60Hz) and 45 rpm (81 Hz, available with the upgraded power plants), but will not provide "speed control" in the sense of fine-tuning the speeds. The PS Audio sounded better than the original VPI PLC in my system, but the SDS sounds better yet.

If your TT uses AC motor I would go for a VPI SDS. The SDS does more than just condition power, it also allows very fine adjustment of motor speed and automatically lowers voltage after start up to reduce motor vibration. The PS Audio power plants can only change output frequency in steps of 5 Hz which is too coarse for speed adjustment.

If you use DC motor than I would choose a PS Audio power plant. A CD motor must be feed by a power supply. You won’t be able to adjust its speed by changing AC frequency and you cannot run its power supply at reduced voltage. So the two most important features of the SDS is unless in this case. A PS Audio power plant will give you the same voltage regulation as a SDS except it is more powerful. You can plug other equipment to a power plant in addition to your TT.

I also use the VPI SDS with my turntable to good effect. Yes it does make a significant difference.

This thread reminds me of something else that I've yet to experiment with & had forgotten about. I've seen a special AC cord for turntable controllers offered by Acoustic Sounds catalog; they claim significant improvements therewith. I surmise that possibly any one of my numerous upgrade AC cords lying around might also be worth trying in that respect? Can anyone share their experiences?

The VPI PLC is not well shielded and will cause hum in your system unless it is kept well away from your signal path. This limits your placement options. The SDS is OK.