Audio Interface Mode (AIM)
Introduction
The audio interface mode (AIM) adapts Symphony I/Oʼs hardware and software interface to the primary host system (the DAW or hardware device) that youʼre recording with. The following audio interface modes, described below, are available with the latest Symphony I/O firmware and software release:
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Symphony - to connect to Symphony 64 Thunderbridge and Symphony 64 PCIe cards. |
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Pro Tools HD - to connect to Pro Tools HD, HD Native, and HDX PCI cards. Symphony I/O may be controlled from a Mac via USB, though the Mac connection isnʼt required for audio operation. |
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USB Audio - to use Symphony I/O as a USB Audio interface with an Apple Intel Mac. |
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Standalone - to connect Symphony I/O to recording devices and other host systems via ADAT, S/PDIF or AES inputs and outputs. Symphony I/O may be controlled from a Mac via USB, though the Mac connection isnʼt required for audio operation. |
Setting the audio interface mode
To set the audio interface mode, press and hold the front panel right-hand encoder. The currently selected audio interface mode is shown on the OLED in solidly illuminated text. Select the desired audio interface mode by turning the right-hand encoder - inactive audio interface modes are shown in flashing text. Once the desired audio interface mode is shown, press the right-hand encoder to confirm the selection. Symphony I/O will re-boot in the new Audio Interface Mode.
The currently selected audio interface mode is also indicated in Maestro's Device Settings tab. When connecting multiple Symphony I/Os to Symphony or Pro Tools PCI cards, be sure set the audio interface mode on each unit first.
Parameter Storage between Audio Interface Modes
When switching between audio interface modes, all settings are saved independently for each mode. For example, it's possible to configure different routing for Symphony and Standalone audio interface modes and freely switch between them using the front panel control described above. Note that calibration settings for are saved independently for each audio interface mode.
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Symphony I/O has been designed to seamlessly interface with the Symphony 64 Thunderbridge and Symphony 64 PCIe cards. All audio and control data is transmitted via Apogee PC-32 cables (included with the Symphony 64 Thunderbridge or PCIe card). When audio interface mode is set to Symphony, the basic signal flow of Symphony I/O is shown below. 
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Symphony I/O may connect directly to Pro Tools HD, HD Native, and HDX cards, using Apogee PC-32 or Avid DigiLink cables. Digital audio and clock configuration data, such as the session sample rate and hardware clock source, is transmitted via the PC-32 cable (referred to as a DigiLink cable in Pro Tools documentation). Software control data between Symphony I/O and Apogee Maestro software is transmitted via a USB connection. Connect Symphony I/O's USB port to a USB port on your Apple Mac to set these parameters in Maestro:
- Calibration
- Meter Configuration
- Digital I/O format
- Mic Pre settings such as phantom power, high pass (if a Mic Pre I/O Module is installed)
Once settings have been completed, USB may be disconnected, as it's not required for operation with Pro Tools. These Symphony I/O parameters may be set using the front panel encoders:
- Speaker and Headphone Output Levels;
- Mic Pre Input gain (if a Mic Pre I/O Module is installed).
These parameters are set from Pro Tools software:
- Clock Source and Sample Rate;
- Audio routing.
When audio interface mode is set to Pro Tools HD, the basic signal flow of Symphony I/O is shown below.
Pro Tools HD on a Mac
Pro Tools on a PC
USB Audio Interface Mode
Symphony I/O may be used as a USB Audio interface with any Apple Intel-based Mac. All audio and control data is transmitted via the USB connection to the Mac. 
USB Audio Interface Mode is restricted to 16 channels of input & 16 channels of output, and maximum sample rate of 96kHz.
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In the case where the digital host system isn't computer-based (or is a computer-based system that interfaces with Symphony I/O using standard digital I/O such as AES or Optical), Symphony I/O's Standalone mode offers the ability to route any I/O Module input to any I/O Module output. The most common Standalone application is the use of Symphony I/O as a standalone A/D - D/A converter, where analog inputs are routed to the I/O Module's AES or Optical outputs and AES or Optical inputs are routed to analog outputs. Software control data between Symphony I/O and Apogee Maestro software is transmitted via a USB connection. Connect Symphony I/O's USB port to a USB port on your Apple Mac to set these parameters in Maestro:
- Calibration
- Meter Configuration
- Digital I/O format
- Mic Pre settings such as phantom power, high pass (if a Mic Pre I/O Module is installed)
Once settings have been completed, USB may be disconnected, as it's not required for Standalone operation. These Symphony I/O parameters may be set using the front panel encoders:
- Sample rate and clock source
- Speaker and Headphone Output Levels;
- Mic Pre Input gain (if a Mic Pre I/O Module is installed).
When audio interface mode is set to Standalone, the basic signal flow of Symphony I/O is shown below. 