There are a lot of reasons why you may not be hearing sound. Here are some troubleshooting steps you can try.

• Press the GO key on Sinfonia's MIDI keyboard. If you do not see any movement in Sinfonia’s player window, see the steps below regarding resetting the MIDI keyboard. (Be sure that you are playing a song that is sufficiently long and loud to test this!)
• Make sure that your theater’s sound system is turned on and working properly. Try connecting the 1/4" cables you are using with Sinfonia to some other music device (like a synthesizer keyboard).
• Note that with the Firewire 410 audio device, there are a series of green lights in the front which indicate that the Firewire 410 is receiving a signal from the computer. If you see the two leftmost green lights lighting up, the Firewire 410 is likely working- please check the connections to your sound system.
• Plug the headphones you are keeping near the Sinfonia system into the headphone jack of the firewire audio device. Make sure the headphone volume for that jack is turned up. If your headphones have a separate volume knob, be sure the headphone volume is turned up as well. If you hear sound in your headphones, the firewire device is likely working- please check the connections to your sound system.
• When the firewire device is properly connected and turned on, you will see a solid blue light in the top right corner. If you see a blue light that is flashing, the device is plugged in, but not turned on. Press in the power switch next to that blue light and restart the Sinfonia computer.
• Listen closely to the laptop: are you hearing the sound coming from the laptop speakers? If so, do the following:

1. From the player window of the laptop: hold down the Command key on the Apple keyboard and press and release the Tab key until Terminal is the highlighted option. (The Command Key also sometimes has a clover symbol and/or an Apple symbol.)
2. Hold down the Command key and press Q to quit the Terminal. You will be prompted with a box asking if you want to close the session; click "close".
3. Move the mouse down to the bottom of the screen and click on the icon "Audio MIDI Setup". When the Audio MIDI Setup window opens, click on the tab labeled “Audio Devices”.
4. In the top right corner. you will see two drop-down boxes for “system Output” and "Default Output". Change both boxes so that either Firewire 410 or Profire 610 (2) is set in each box.
5. Click the red button on the top right corner of the Audio MIDI Setup window to close the window.
6. Move the mouse down to the bottom of the screen and click on the icon “sinfonia script”. Sinfonia should relaunch and the sound should play back out of the selected firewire audio box.

If none of these steps solves the problem, try the following:

1. Quit Sinfonia by clicking on the Quit button, and shut down the computer.
2. Unplug the firewire cable which connects the firewire audio device to the computer. The blue light on that device should go off.
3. After the light goes off, wait 3 seconds, and then plug the firewire cable back into the device and the computer.
4. Restart the computer, and click RMS to relaunch Sinfonia.

There is a known bug relating to the operation of this device and how it communicates with the Apple operating system. Occasionally, the internal settings of the Firewire 410 may change so that the music it plays back appears to be a little more than a 1/2 step higher in pitch from how the music should normally sound. If you discover this to be happening, do the following:

1. From the player window of the laptop: hold down the Command key on the Apple keyboard and press and release the Tab key until Terminal is the highlighted option. (The Command Key also sometimes has a clover symbol and/or an Apple symbol.)
2. Hold down the Command key and press Q to quit the Terminal. You will be prompted with a box asking if you want to close the session; click "close".
3. Move the mouse down to the bottom of the screen and click on the icon "Audio MIDI Setup". When the Audio MIDI Setup window opens, click on the tab labeled "Audio Devices".
4. Be sure that in the Audio MIDI Setup window, the "Properties For" selection is set to "Firewire 410".
5. Towards the bottom of the Audio MIDI Setup window (in the section labeled Audio Output) is a setting labeled "Format". The current setting for 
Format may be "48000.0 Hz". This is incorrect. Click on that box and select "44100.0 Hz" to be the Audio Format.
6. Click the red button on the top right corner of the Audio MIDI Setup window to close the window.
7. Move the mouse down to the bottom of the screen and click on the icon "sinfonia script". Sinfonia should relaunch, and it should play back at the correct pitch and sample rate.
8. The issue here is that the sample rate can sometimes change by itself, possibly related to a power surge or similar event. Make sure to test the 
system before starting rehearsal (and especially before starting a 
performance!). If you notice the same half step discrepancy, repeat the steps above.