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!
arsh
I had a Classic 1 with a Zepher mk1. When I purchased the SDS, I thought it improved the sound quality enough to keep it. I notice the improvement more with the power conditioning that it does than the speed control. I do have the SDS plugged into a power conditioner also. I do like changing from 33 to 45 with a push of a button.
what about using the cheaper alternatives to the SDS that correctly maintain speed?
Thanks for your reponses. Is the strobe disc that comes with the SDS good enough?
I find the strobe disk a little hard to read with my old eyes. Using a digital tack from Amazon for only $16.00 makes it easy for the fine adjustments that the SDS is capable of.