How good is the Obsidian plinth of Technics SP10 ?


Recently I heard an SP10 MK2 playing music at a friend's place. It was mounted on the stock Obsidian plinth. It actually sounded very good. I wonder how good is the Obsidian plinth compared to:

1. Typical after market birch ply plinths ?

2. Custom designed plinth like the Panzerholz plinths made by Albert Porter ?

Any ideas ?
pani
To Downunder:  The two subs I am using in stereo mode are the Seaton Submersives. They are dual 15" subs with a 3400 watt amp each. They are flat to about 10-14 hz...So they can definitely excite the cartridge/tonearm/table system into feedback with a record with a lot
of low frequency info at high volume (think Donald Fagen - Morph the Cat)...It never happens with just my main speaker running full range (Green Mountain Audio Continuum 3) which have a -3db at 27Hz.
@lewm

feets Audiotechnica AT 636 does not exist if I search on the internet.

Are you sure of the acronym or maybe are you confused with the AT 615?

best-groove, you overlooked that not Lew but Nandric mentioned

AT 636 footers. I own 4 of those so even their plural exist. But

this does not imply that they are available on eBay or elsewhere.

BTW I need to clean the cover of my Obsidian each week. Those

particles are everywhere and like death unavoidable. So without

the cover the dust has choice between platter or records...

@best-groove i got a set of 4 (Audio-Technica 636) in original box in mint condition if you need them. They are quite rare and very nice pneumatic insulators. 

Dear chakster, the Germans lost 3 wars because they combat on

4 fronts. You are busy on MM ''f'ront'', MC kind, turntables and,

it seems, also footers.  You must do well financialy ?