Speed regulation - how important will it be?

"The record must be rotated at the correct speed to supply the time axis of the record moving under the stylus. The better the turntable can do this, the better your music will sound."

Exactly.
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I also have this strobe, but it really only tells you what the average speed is. Their could be small variations in the speed, constantly speeding up and slowing down, that the strobe won't reveal. Large flucations would show up as the tick marks drifting first one way and then the other, but I don't think you could see small ones.

Since I believe you have an AC motor, any variations in the line frequency will result in speed flucations. Just because it was 2 when you measured it doesn't mean it will be 2 all of the time. It depends on how well the power company regulates the frequency and how much noise is on the line. This is where the VPI-SDS or PS Audio come into play. Since they supply an unwavering 60 hz signal, the stability should be better even if you don't see it with the strobe.

If it is stability you seek, then you already have the Ps Audio so I don't see any benefit in getting the VPI since it is also a regenerator. The VPI does perform some other functions such as ramping up the motor so you would need to decide if it is worth it to you. If you use the PS Audio be sure it is set for 60 Hz and the multiwave stuff is turned off.

Well said, Twl! My short pontification is that the better the speed control the better (more accurate) the pitch, therefore the better the music. I have the VPI SDS and am using it in conjunction with the VPI HW-19 Mk. III table. My music IS better using this unit. To me, well worth the price of admission.

Virtually all turntables have some speed control issues. Most of the better ones keep all the variations in a very limited range with little or no audible effect(with most people). However, I am always amazed at what seemingly insignificant things can do to improve the sound quality. I would state that anything that you can do that would smoothe and steady your platter speed is going to be beneficial. Even if your TT is at a good capability already. I know of several people with state-of-the-art turntables, who have found audible benefit from changing power cords on the motor system, changing the caps and resistors and wiring in the motor controller, using better power conditioning or DC battery power on the motors,using different belt materials, etc. When a turntable already has "excellent" speed control, one might wonder how doing any of these things can improve it. I don't know all the exact reasons, but in certain cases the changes are audible. I suspect that the changes are in fact making the motor and drive system operate smoother and more stable.

To paraphrase from an IAR article I once read, the record only supplies half the information in the music. It supplies the amplitude information etched into the vinyl. It relies upon the turntable to supply the other half, which is the time domain of the music. The record must be rotated at the correct speed to supply the time axis of the record moving under the stylus. The better the turntable can do this, the better your music will sound.

I can't say what will improve or degrade the sound in your particular system. Certain changes may make improvements, or may not, or they may or may not be heard at the speaker. You have to experiment on your own system to see what helps and what doesn't.