Been searching quite awhile now and can't come up with a definitive answer, today's SDOTD is a Tascam us-1200. I'm already running one, is it possible in Sonar Platinum on a PC to run two of them simultaneously? Most of what i've read says no-but that sometimes multiples of the same interface will work. And they say in Sonar there's the WDM option, which supposedly has low latency, but i wanted to see if anybody had experience in this on how much it changes. The 6-ins i have now works for me, but having the option of more would be nice on the rare occasion i get together with others to play and record. So this isn't essential, but adding to what i have at this cheap price is a more feasible option than dropping $250 on the 16x8 version.
Thanks!

Trouble is you cannot do 2 ASIO interfaces. 
WDM mode is not the greatest. 
I did a bunch of loopback tests of a few interfaces. 
In ASIO mode my Tascam us1641 scored perfectly..But in WDM mode the sync was way out. This is bad news for overdubbing tracks. 
That said, it's all fine as long as all your doing is recording, say a live band, and then you swicth to using one interface in ASIO mode for overdubs. 
 
I'm not sure what you will see when you hok two identical interfaces into Sonar in WDM mode. 
I had no problem using my TAscam us1641 along with our Yamaha mixers USB stereo out. Sonar gave me both as input options. 

Ok thanks. I plan to just use it for live stuff or big recordings where there will be a few of us at a time, and then can do overdubs later using just one of them in ASIO, so sounds like it should work for what i intend.

Got the us-1200 delivered today and plugged it in, as expected only one showed up in ASIO mode, but both were there in WDM mode. Didn't get to play anything, just had time to make sure they were both visible so far.

I run a Tascam US-1641 and a US-1800 over Asio4All (which is a wrapper
over WDM). This allows multiple interfaces.
 
I use this setup purely to record live bands, so the poor latency is not an issue.
 
It is true that the tracks recorded by the two interfaces are NOT in sync,
but tracks originating from each individual interface ARE in sync with each other.
 
So I add an identical offset to all tracks of one or other of the two interfaces
when I mixdown. Apart from this minor inconvenience, I have recorded up
to 28 tracks at a time with no problem.

Cactus Music
I'm not sure what you will see when you hok two identical interfaces into Sonar in WDM mode. 
I had no problem using my TAscam us1641 along with our Yamaha mixers USB stereo out. Sonar gave me both as input options. 

Windows already doesn't like it. I tested with my two US-1641s connected, Windows "Install driver" dialog popped up multiple times.
 
US-1641 + US-1800 works fine in WDM.
 
US-16x08 doesn't work AT ALL with anything other than ASIO in Sonar
(I tested it with S8-8.5.3, SX1-X3, SPlat Lexington)
yet it works with MME with Audacity - but OK, that's 32-bit.
 
Very, very annoying. 1.04 drivers, the latest.

In Windows, everything works with MME as its a Windows Multi Media Extension, Disadvantage is very poor latency and its 32 bit,

WDM should work but whether the drivers provide low latency for recording is another quetion.

ASIO 4 all has been found to cause problems with existing ASIO drivers that are installed.

For those running what we call a "Pro" system, ie. an audio device capable of running a low latency ASIO driver, the latest recommendation is to delete ASIO 4 all from the computer entirely. We've even found that running High Definition drivers for onboard sound cards like RealTek and nVidia can be a disrupting influence and uninstall those. Even deleting HDMI connections to your (TV) monitors has been found helpful in providing stability where nothing else would work.