One turntable with two arms, or two turntables with one each - which would you prefer?

Why do we seem to think “hardness” is the most important criterion for a material used to build a plinth? 

lewm,

It's not. Just stating the physical characteristic of Panzerholz. That characteristic produces very clean and crisp parts as oppossed to say plywood or MDF. 

I would imagine that the hardness would contribute to the speed at which mechanical vibration travels throught the material (velocity).

I am not in anyway meaning to denigrate Panzerholz, but the prior discussion centered in many cases on "hardness" not just of Panzerholz but of other materials mentioned. And I wondered why. Seems to me that hardness is concomitant with the necessary characteristics of a good plinth material but is not THE reason why a material is good or bad for a plinth. Yes, a plinth ought to be good at dissipating energy put into it by the turntable chassis. By the same token, granite ought to be good too, but many (not including Pindac) have found it to be less good than other choices. Until now, I did not realize that Pindac had a favorable opinion of granite. For that matter, slate might seem to be a good choice, and it is what I chose back when slate was all the rage and OMA were selling slate plinths for a wide variety of turntables. (Given my contrarian nature, I created my plinths for the DP80, SP10 MK3, and Lenco "from scratch" but using professionals to do it the way I wanted.  When I wrote about my slate adventure on line, OMA were not happy with me.) I am satisfied with the outcome, but I am not going to claim slate (Pennsylvania black variety) is the best choice. Around that time, Albert Porter was selling Panzerholz plinths for SP10s Mk2 and Mk3. I’m sure those are excellent too. It’s interesting to me that Panzerholz is good because it’s made by glue-ing together layers of material. Glue creates a boundary between layers. Energy arriving at the glue line would be partially reflected back and partially transferred across the boundary. I am guessing that because the whole is compressed under very high pressure, that potential issue is ameliorated.  Another choice is concrete; I have used large square pavers from Home Depot as audio shelving.  It works pretty well for that.  Would be hard to conceive of making a plinth of it but fun to try.

I have a table with 2 arms (feikert blackbird, Kuzma 4pt and schick 9,6.  Koetsu Onyx on the Kuzma arm, Ortofon SPU grand royal on the Schick.  I also have a Rega P8 with Hana Umami Red.  Phonostage is Manley steelhead so I can plug all 3 in at once. I really like them all.  If you have the room, I say the more the merrier.  I find a time and place for all of these sounds coming from these setups.  Yes the Kuzma/Koestsu is the best but I still have a lot of fun listening to the others and get a different sound and vibe from them.  I would have more turntables if space was no issue.  I think probably 2 turntables is more fun than one with 2 arms.  Get tables you can add an arm to and maybe you can end up with 4 arms!

As Stated within this Thread, I have no desire to return to a Mass Plinth Material as my regular used Plinth for the TT of choice.

It has been made known within this thread from the time (which is 20+ Years ago) that I chose Granite as a Plinth Material; I had been demonstrated around this time both Granite and Slate as a Plinth Material with a same TT model mounted.

Granite was preferred over Slate and that was the route I went down, I even made it known that the personalities demonstrating Granite, might also have been a factor in my decision being made. (It is all too distant and not able to be accurately recollected, the only realness is, I chose a Granite Plinth for a Garrard 401, and shortly after had a SME IV purchased to use with it, and possibly a High Output MC ??).

As stated within this Thread, I have a very heavy Slab of Slate, enough for Plinths for Two TT's or a Multi Arm Design, I have no desire to have a Mass Plinth in use for my chosen TT any longer, so this as an option is buried.

As stated within the Thread I own a Mass Plinth, being Corian, but the TT it is used with is superseded and is used for demonstration purposes only of an Idler Drive TT.

Along with the above I have also heard a few produced Polybentonite Resin structures formed to function as a Plinth Design on a few different TT's, this is a Mass Plinth and measures favourably to Panzerholz for Damping but dissipates quite differently. The Polybentonite Resin Plinths are similar to recollections of other Mass Materials used for a Plinth. To my sensitivities I detect a colouration present not dissimilar to a Cabinet Speaker Colouration, for myself this has become quite unattractive when detected, to the point of feeling something present is overbearing.

Panzerholz as a Plinth material is not an idea that comes from myself, I was introduced to it, and was impressed, on follow up encounters that impression grew, as my recognising the attractive properties on offer during a replay were being proportionally attributed to the P'holz. An extended period of experiencing it and having seen others 'deny it' and then 'adopt it' has affirmed to myself, there is a New Plinth Material I am needing to introduce.

For me it is the airiness and unconstrained flow, the ease the presentation takes on, and the clarity that is very attractive perceptions to be encountered. 

As stated within this Thread, I have a Plinth produced from P'holz, that is out on loan to those who owning a TT that suits the design and can mount their TT on to it.

If their Tonearm of choice is not able to be mounted the offer is available to assist with enabling the individual expressing an interest to hear their TT in a P'holz plinth.

There is not a penny for myself to make from such an offer, it is just an extension of the social activities I engage in with HiFi and other enthusiasts, either known or not known to myself. This is something I would not consider for any other Plinth Material, but for some reason the P'holz material is seemingly worthy.

The only reason I can see, why Plinth Materials are presented as a subject within this Thread, is because a design for Two Tonearms might require a New Plinth to be produced, so an individual contemplating this is to be aware of the options on materials. Indirectly a user of a Typical TT > Tonearm set up, might become curious as to how different materials as a support for a TT > Tonearm might impact on their set up. Plenty of us are from that background, so no need to discourage it.