will grado hum?

Dkzzzz, you don't need to. The hum with Regas and Grados is caused by the ungrounded parts, and is easy to solve.

The other way to fight the excessive hum would be to glue a sheet of Mu-metal to the mat or platter.

Thanks Ralph.

Piedpiper, sure. I ran a wire from the case of the motor to the bearing of the platter, and from there to the base of the arm, so that they were all grounded. I had to scrap some of the plating off of the motor case in order to be able to solder to it.

Atmasphere,

do you recall what exactly you did to the Regas to cure the grounding issue?

I've seen this with Regas, but we found that we were able to fix some grounding problems on the Rega and then there was no hum at all.

I have a Grado Ref Sonata, have never used it on an Alphason, or any S shaped arm, but I did have a hum problem when I was using it on a Heybrook Turntable. The problem only occurred when the cartridge approached the center (ie end) of the LP which is nearing where the motor is. My research indicated they pick up hum from AC motors. Using the same cartridge on my other tables (with DC motors) was no problem at all. It's as quiet as any cartridge I've used, and quieter than some.

No problem with Grado Blue and S-shaped Vintage Rega Arm.
I say no problem because in order for me to hear Grado hum I have to turn Volume to 3 o'clock, which I would never do while listening.

No problem with a Grado TLZ and an Alphason HR-100S "S" shaped tonearm.

I'm using my Grado Ref. 1.2K price range with my older VPI deck,and a Morch UP-4 Arm and have no problems,But you must shield with a high quality phono cable to minimize any of this.
I have used unshilded cables here and things don't work,But I had to try out several from USEDCABLES lending library to get the right match.