Trying to reduce noise while listening to tube phono

+1 @lewm Who, unlike me, may have the technical expertise to explain *why* dedicated AC lines helped with noise issues. Thanks for your cogent summary of the way AC lines can be a factor.

Agree that phono stage design is likely a culprit in the OP's noise situation. But I'm sold on dedicated AC lines, whether I can explain their efficacy or not!

What is the reason to have unshielded tonearm leads?

I bought the M2-12R from the dealer who suggested rewiring it in this manner for better sound. It really makes a difference.... SME's wire has never been their strong suit. I'm super happy with the arm so I would definitely look everywhere else for solutions rather than rewire.

If you live in a low RFI environment, you might not suffer for lack of shielding.  I use unshielded tonearm leads in my suburban environment, for some of my arms, and I don't perceive a problem.  Which is to say that my tonearms using shielded wire sound the same as those using unshielded wire, in terms of RF noise. If you live in a city or industrial area, shielding is a good idea. Furthermore, I would think that the SME arm wand itself acts as a sort of shield for wires traveling within it.  Not so, once those wires exit the base of the tonearm.  On the other hand, I have never read that SME used inferior wires.  Is there any reliable source for that info? (Is there any reliable source for anything in audio?)

First rule of shielding is to protect the signal “ground” also. You need to replace your simple unbalanced fake-“shielded” cable from your tonearm to the phono stage with cables that have fully shielded twisted pairs, one cable per channel, such as Belden 1696A. The shield drain wire connects to the tonearm ground at the turntable side, and to the phono stage chassis ground at the other side. Make sure the tonearm ground is isolated from the turntable chassis. All interconnects should be made in this way for line level signals, except the shield drain wire only connects to chassis ground at one end - with the preamp usually being the most suitable end. 

Regarding the SME wire..... I was going to replace the tonearm cable only which just from anecdotal evidence from owning a couple of their arms in the past and also from people I've known that have upgraded from the stock cable, aren't great.  The dealer suggested he had really good results with a rewire from RCA to the headshell so I did it.