The professional analog audio inputs and outputs are fully balanced and adapt to consumer or professional operating levels at the touch of a button. Analog or digital source selection is made at the rear panel.

For digital interfacing, the 320D contains a high quality 24 bit low noise codec to receive digital audio and transmit digital audio. Once the incoming digital audio is converted by the DAC section, it passes through the compellor as normal audio. The audio output is then converted back to digital by the ADC section of the codec.

The rear panel AES3 jacks are standard professional 110 ohm interfaces. There is no word clock input or output. Synchronizing is done from the AES3 input signal or an internal clock. When a digital input is present, the output is synchronized to the input sample rate. If no digital input is present, the digital output automatically locks to the internal default sample clock. The user can specify the sample rate by changing the internal crystal. Spare crystals for 32kHz, 44.1kHz, 48kHz, and 96kHz are supplied with the unit free of charge.

The model 320D codec translates the -20dBfs level of the digital audio source to the 0dB reference within the Compellor circuits. The average output levels will target around -20dBfs. The selectable peak limiter's threshold translates to -6dBfs. Thus, no digital audio output peaks will rise above -6dBfs when the limiter is on. The combination of averaging the level around -20dBfs and holding peaks below -6dBfs packages the audio perfectly for natural sound quality and for most transfer or transmission purposes. For example, the digital audio would be ready for direct input toan MP3 encoder, HD recorder, Broadcast digital STL, .wav file, etc.

Two properties of audio that can cause problems are the average level (the "loudness") and unpredictable peaks that can clip. The Compellor handles both problems for you, fitting the sound into an ideal sound envelope package.

The Compellor's "Frequency Discriminate Leveler" (FDL) section with the "Dynamic Verification Gate" (DVG) and the "Silence Gate" (SG) slowly corrects the volume level of an audio stream with very complex algorithms that hide its work. It works differently at different frequencies, for example. It locks up when the sound stops and resumes instantly when sound reappears. When you listen, you know the levels are made more even, but you don't perceive the levels are shifting.

The Compellor's Variable Slope Compressor with the "Dynamic Recovery Computer" and the "DVG" work on top of the leveling platform to add adaptable compression that helps you match the texture of changing audio sources. Again, you don't hear "pumping" or other audio artifacts, just very natural sound that is evenly consistent in loudness.

The Compellor's limiter acts on peaks that shoot beyond typical audio crest factors. Extremely peaky sounds will be brought into an envelope that is easy to handle by any analog or digital recording or transportation medium including digital codecs.