Vibration Theory - Isolate or Drain?

It varies, and makes no sense. You must experiment.

Look into the Mapleshade Audio solution. Used it under CDP's, DAC's and amps and have achieved wonderful results with all.

I use Herbie's Tendefeet under everything electronic. Cones will "drain" in the vertical plane while the Tenderfeet "drain" and absorb in all planes from the point of contact. Can't say you'll have the same results but it works for me.

But I got a better result putting the CD player on a marble tile resting on 3 tungsten carbide ball bearing resting on 3 FIM saucers.
Stanwal (System | Reviews | Threads | Answers | This Thread)

I use the FIM saucers with tungsten carbide balls as well. Shelf resting on top of the ball bearing (rather than another saucer).I use a different shelf material though.

Playpen, The nanomounts are placed (ie. glued) onto the cartridge and then the cartridge is attached to the tonearm. The triple points are on the cart with the single point touching the tonearm (you must not overtighten the cart to the tonearm). This is just like the system you currently use to drain vibration from your Rega's plinth only in miniature. With the tonearm you place the nanomounts between the base and the arm mounting board. This is not an easy process but I felt it improved the sound clearity (ie. reduced resonance)on my Clearaudio Champion Level Two and Unify Tonearm/ Ortofon 2M Black.

If you like your present rig and plan to stay with the tonearm I believe the nanomount system is worth it. I've tried tweaks from setup guru's over the years and I have had the best results from Pierre Sprey of Mapleshade. He has many no cost tweaks on the website and some that you can purchase. I believe that before you spend alot of money on a new cart you should try this solution and it has a money back guarantee. Mapleshaderecords.com