And what would be the problem that you are solving?
In a word Motor vibration.
As 13 Duke says, how much of latest Radikal was a better rubber washer!!
I would say a tuning fork is what we don't want.
We can separate the deck into two zones, Isolation and playback. (A boundary diagram for any engineer reading and use to creating DFMEA's)
The chassis holding the bearing and arm is the playback zone, which in an ideal world will experience no external vibration. The motor, plinth, top plate etc are all on the isolation side of the equation.
We don't want any vibration crossing the boundary between the two, as that would disturb the interface between the record and the stylus., causing distortion or colorations and loss of detail retrieval.
The motor has two functions, spin at a constant stable rpm, have minimum vibration so as not to disturb the playback area. I consider the power supplies since Lingo have managed to get a good constant speed. (yes they have got better but how much does that add to the SQ) With each version Linn have provided better motor control, to reduce the vibration.
So look at from a another angle (cheaper than yet another expensive PSU upgrade) Accept the motor will vibrate, now manage that vibration, so that it doesn't make it's way into the playback area. Now the type of PSU becomes irrelevant. (Ignoring speed accuracy).
On my second deck I've been trying out some mods. The top plate is now separated into two. One to support the motor, the other the springs/chassis. The motor has it's own mount and is anchored down to a strengthening spar added to the plinth. Motor vibration is taken down and away into the plinth, which is grounded to the shelf with rubber feet, not a tramoplin.
Any vibration that circulates around the plinth, now has a much longer path to enter in the main top plate, the longer the path and the more adsorbate materials it passes the more energy that is lost. I 'm also trying out a non metallic chassis, it's a two part chassis, along the TP Akula concept.
So making a one piece machined plinth does seem a bit counter intuitive. Back to the tuning fork, it will all sing and ring together, perhaps the extra mass has some dampening.
Testing/comparing isn't a simple apples to apples task, my other deck is at Radikal 1, Keel, SE, Kandid, Urika1, so all Linn. The second deck runs Ekos2/Krystal original arm cable, Lingo 1, Cirkus/Tranquility.
The DIY deck in a separate system was sounding good, enough to make me put them side by side and compare. For sure the Linn deck was better, but not by enough, some was tonal difference. So I started swapping parts between the two decks. Removed the Urika and Tranquility.
Having done the Lingo to Radikal demo in the past when I ordered mine, I wasn't missing much on the deck running Lingo. So I swapped the arm and cartridges over.
In Linn hierarchy, the Radikal/Keel deck should still win, even with the lesser arm and cart.
The difference was smaller now and the DIY deck was just as musical. Putting a T Cable and Tranquillity back on saw it sounding the better deck. It lost maybe a little of the slam and kick of the Linn deck, in similar way a Kore does to a Keel. (For me they are just as musical as each other).
I wasn't missing the Radikal it seemed, so I feel as a motor mod it works and I perhaps don't need to bay a second Radikal now. (May add a 3rd party one, to try a loose even more vibration)
I do need to take the chassis on to the next design level as combination of machined aluminium and carbon printed support. Again better dividing the isolation and playback boundaries.
Been a busy couple of weeks