SDS or phono stage

I have a VPI Scoutmaster with Soundsmith Zephyr Mk II cartridge, jmw memorial arm, a stainless steel vpi record clamp, playing through a Musial Fidelity KW500 integrated amp with on board phono stage. Sounds quite good, but my question is this: would I be better off at this point adding an SDS or an outboard phono stage? Or both? In what order? Thanks!
The SDS is more of a speed controller than a line conditioner. Mine is plugged into a conditioner. If you own a VPI table and you want to get the performance from it, you must have the sds. Its like an automatic transmission for a car. Just get it. Then, shop for the phono stage.
Thanks Cerrot. Now the only problem is finding one. None of the retailers seem to have any.
Arsh (and Lwin), The SDS is an AC re-generator. Think of it as an amplifier that puts out 120V and 60Hz (or whatever variation from those baseline parameters is needed to make your tt run at precise 33 and 45). Thus it does more than any typical power conditioner, most of which are just noise filters with or without an isolation transformer, unless your power conditioner is also an AC regenerator. Lwin, your balanced AC power does not substitute for the SDS or other similar power regenerating motor controller. Moreover, a good motor controller also makes the tt motor run quieter, if properly adjusted. Even further, the AC regenerator prevents motor noise from getting back on to the AC that serves your other noise sensitive components. So even if speed is bang on without the motor controller, there are still benefits to be had.