Simultaneously Using Two Audio Interfaces: Is It Possible and How to Achieve Seamless Performance

The world of audio recording and production is continuously evolving, and one frequently asked question is whether it is feasible to use two audio interfaces simultaneously. The answer, in short, is yes, it is possible, but there are several technical considerations that must be made to ensure a seamless experience without delay. This article will explore the challenges and solutions associated with using two audio interfaces together, focusing on the key points that need to be addressed.

Drivers and Software Support

To achieve the goal of using two audio interfaces simultaneously, the foundation of your setup must be strong in terms of driver and software support. Windows users can benefit from using ASIO drivers, which are specifically designed to manage multiple audio interfaces efficiently. ASIO (Audio Stream Input/Output) is a low-latency audio driver that provides a direct connection between your DAW and your audio interface, ensuring high performance and minimal latency.

For macOS users, the built-in support through the Aggregate Device feature in the Audio MIDI Setup utility is invaluable. This feature allows you to use multiple audio interfaces as a single virtual device, making synchronization and management much easier. Some Digital Audio Workstations (DAWs) also support ASIO aggregation, further enhancing the capability to handle multiple interfaces effectively.

Latency Issues and Synchronization

One of the primary challenges when using two audio interfaces simultaneously is latency. Each interface may have its own latency, and the clock sources can vary, leading to synchronization issues. Audio drift and phase problems are common if the interfaces are not perfectly synchronized.

To minimize latency, you should ensure that the buffer sizes set for each interface are the same. Buffer size is a critical parameter that can significantly affect performance, and tweaking this setting can help reduce latency. Synchronization can be further improved by using a word clock or timing reference, which can help ensure that both audio interfaces are in perfect sync.

DAW Configuration

It is essential to configure your DAW to handle multiple audio interfaces correctly. Most DAWs are designed to support multiple devices, but you need to ensure that the settings are configured to use both interfaces effectively. This may involve adjusting routing, input/output settings, and other parameters specific to your DAW and the audio interfaces you are using.

Practical Considerations

Using two audio interfaces can also bring additional practical challenges. For instance, your laptop's processing power may be pushed to its limits, leading to performance issues. It is crucial to ensure that your system is robust enough to handle the increased load.

Compatibility is another consideration. Not all audio interfaces are designed to work seamlessly together. It is best to verify that the specific models you intend to use are known to work well in tandem, especially if you are expecting to use them in a critical project.

Better Solutions for Minimal Latency

While using two USB interfaces can be a convenient option, USB protocols, particularly UAC (USB Audio Class), have quirky limits and can introduce issues when used for real-time audio streaming. Using FireWire interfaces or optical ADAT links can offer better performance with less latency.

Connecting your two interfaces through an optical ADAT link is a robust solution. This approach allows you to input one signal into both interfaces and achieve a time reference for audio alignment. Even if the interfaces are identical, the USB chain can introduce unequal delays, which can impact performance.

Another effective solution is to use the interfaces' internal monitor mixing matrixes. By chaining one stereo mix output from one interface into the second, you can avoid latency introduced by routing through the DAW. This approach requires using the manufacturers’ control panel software rather than routing through the DAW, which may introduce additional latency.

For those with S/PDIF outputs, a stereo mix can be transferred directly between the two interfaces, sidestepping the need for TRS or XLR channels. Synching on the S/PDIF word clock can further enhance synchronization and minimize latency issues.

Conclusion

In conclusion, while it is possible to use two audio interfaces simultaneously, achieving a seamless experience without delay requires careful setup and configuration. If you encounter latency issues, it is advisable to stick to one interface or explore more robust solutions like FireWire or ADAT links. By understanding the key points and considering the practical challenges, you can maximize the performance of your audio setup and ensure a high-quality recording experience.