2 Thunderbolt displays MBP = sound coming from both displays?

Question

Hello everyone,
So my question is: "Is it possible to make my both thunderbolt displays to produce sound to? Currently I can choose either one of them or my macbook pro, but maybe somehow it's possible to make it go thru both of the displays?"
They are connected to macbook pro via thunderbolt.

Answer 1

Success!!!
Okay this got a bit complicated, but I found the right mix of software to make this work.  So here's again the hardware and software setup:
TD = Thunderbolt Display
CH = Channel
MBP = MacBookPro
L = Left Speaker
R = Right Speaker
TD1 (L/R)    |    TD2 (L/R)    |    MBP (L/R)
iTunes => SoundFlower => Jack => Aggregate Device => 6 speakers!
Stereo audio only has 2 channels (left and right).  So the trick is to get 2 system channels to map to the 6 speaker channels I have. 
Step 1: Setup an Aggregate device to merge the 3 sets of speakers into one aggregate. 
1-1: In Lion, go to Apps > Utilities > Audio MIDI Setup
1-2: Click the + in the bottom left and select Create aggregate device.
1-3: Select the 3 devices: Built-in Output, Display Audio, Display Audio (there are 2)
1-4: Click Configure Speakers
1-5: Select all 3 streams at the top
1-6: Click Multichannel and then select Hexagonal (this gives you 6 virtual speakers in the graphic)
1-7: I don't think this step is required, but map the channels to the right locations.  For me this was a little confusing because TD1 was channels 3 & 4, TD2 was 5 & 6 and, and MBP is 1 & 2.  From top left going clockwise, I selected 4, 5, 1, 2, 6, 3. 
1-8: You can click the speaker for each one to hear a test tone to make sure you have them right.  It's right if the 2 left ones come out of the left screen, the 2 center ones from the center screen, and the 2 right ones from the macbook.
1-9: Right down the numbers so that you know which ones you want for left and which ones you want for right.
Okay, now this is enough to get audio from 2 devices, but stopping here you'd lose your volume control and 4 of your 6 speakers.
Step 2: Install 3 apps (all free):
2-1: Download SoundFlower from http://cycling74.com/soundflower-landing-page/
2-2: Download JackOSX from http://www.jackosx.com/
2-3: Download JackOsX Autostart from http://www.jackosx.com/
Step 3: Setup Jack
3-1: Install Jack
3-2: Start JackPilot and go to Preferences
3-3: Setup input-output device as Aggregate Device that you setup in step 1
3-4: Interface Output Channels should show 6 (6 speakers!).  Set Virtual Output channels to 2 (stereo)
3-5: Uncheck auto-connect with physical ports
3-6: Save changes and start the Jack server if it's not running.
Step 4: Setup Soundflower
4-1: Install Soundflower
4-2: Click the flower in the task bar and then choose JackRouter under the 2-channel at the top
4-3: In Lion, go to Apps > Utilities > Audio MIDI Setup
4-4: Find Soundflower (2 ch) and click it, then on the right select Output and then configure speakers
4-5: Select Stero and then set the left speaker as 1 and the right as 2.  Testing the speakers here will likely do nothing.  That's okay.
Step 5: Finish Jack
5-1: Go to Connection Manager
5-2: Note: this part was a pain -- the UI is funky, so be patient.  Click only how described.
5-3: Open the various sub-sections until you can see Soundflowerbed under the Send Ports and see out1 and out2 (the stereo ports) and the System under Receive Ports and you should see playback_1 thru playback_6
5-4: Carefully single-click out1 then double-click the first left speaker channel.  Single-click out1 again and then double-click 2nd left speaker channel.  Single-click out1 again and then double-click 3rd left speaker channel.
5-5: Carefully single-click out2 then double-click the first right speaker channel.  Single-click out2 again and then double-click 2nd right speaker channel.  Single-click out2 again and then double-click 3rd right speaker channel.
5-6: Close the connections manager
Load up iTunes or something else and play music.  If everything is setup correctly, all 6 speakers should be going with 3 left playing the left channel and the 3 right playing the right channel!
And since you're using Soundflower, your volume controls on your keyboard, etc, should work just fine.  Note: you can tweak your individual volume controls back in the aggregate device setup if you need to fine-tune something.
Hopefully that all worked for you!  Let me know how you made out!