Is it possible to use ASIO drivers with two or more open programs at one time?
I tried ASIO4ALL but it doesn't want to work.
I have a Line 6 Toneport GX and I'm using it's ASIO Drivers.
 
Windows 7 Pro 64, Quad.

AFIK, ASIO doesn't like to share it's drivers. However, I believe there's a setting in Sonar to "Share drivers with other programs" (to that effect), but I've never done that.
 
Take a look at this: https://www.cakewalk.com/Documentation?product=SONAR%20X3&language=3&help=AudioPerformance.28.html

I've made it work in the past, but if the different apps want different sample rates things get goofy.  I keep my Sonar interface dedicated to Sonar.
 
 

You can stream audio from multiple programs through an ASIO driver. The limitation is that you can only use one device with an ASIO driver u less the manufacturer writes the driver to use multiple hardware units. eg RME you can use up to 3 X FF800s hooked together and co troll them all as one it.

If you turn on Share drivers with other programs - in Sonar, what will happen is that only the program with focus n Windows will send audio. If you want multiple programs to stream audio then make sure that setting is turned off in Sonar.

Then it's just a matter of selecting the ASIO driver within the software. Remember that programs like Windows Media Player do not use ASIO drivers as its not a Windows driver model. In that case select WDM drivers. If it's for playback only you shouldn't have any problems.

Mudgel is correct.  you can share multiple programs with ASIO, it is not limited to 1 program, it is limited to 1 device (unless that device has drivres written which make multiple devices look like 1 device; i.e. 2 MOTU units chained together using ASIO drivers look like 1 soundcard to windows).
 
do not try to use ASIO4ALL on any device which already has native ASIO drivers, tho.  uninstall it from your machine!