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SSL 2/2+ General FAQ

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Product Videos

Tutorial videos for SSL 2 and 2+ interfaces can be found on our website:

or YouTube channel:


Differences Between SSL 2 and 2+

Feature SSL 2 SSL 2+
Best Suited For Individuals Collaborators
Mic/Line/Instrument Inputs 2 2
Legacy 4K Switches Yes Yes
Balanced Stereo Monitor Outputs Yes Yes
Unbalanced Outputs - Yes
Headphone Outputs 1 2
Low- Latency Monitor Mix Control Yes Yes
MIDI I/O - Yes
USB Bus-Powered Yes Yes


Headphone Output Impedance

The source impedance (headphone output impedance) of the SSL 2 series is 10 Ω. SSL 2 is designed with professional audio quality in mind, which means that there is ample power to drive a wide range of professional headphones from the built-in headphone output.

For optimum performance, a typical ratio of headphone impedance to source impedance should be 8:1 or greater.


Balanced vs Unbalanced Outputs

Unbalanced outputs carry a single copy of the signal and the ground connection. This means that unbalanced cabling over longer distances can be prone to interference, which can be heard as noise on the signal.
Balanced outputs carry two copies of the signal, that when combined at a balanced input cancel out noise and interference that has been picked up. Balanced outputs should be used for longer cable runs to speakers/devices, as they have lower noise and are better for rejecting unwanted interference.

To interface an unbalanced piece of third party equipment to any SSL balanced input use the following wiring scheme:

  • Positive to Positive
  • Screen to Negative
  • No Connection to Screen

The image below illustrates the comparison:

Balanced lines

This image shows an unbalanced (TS) and balanced (TRS) 1/4-inch Jacks.

Balanced Audio


True Balanced or Impedance Balanced?

The outputs of the SSL 2 and SSL 2+ are true, fully balanced outputs. Impedance balancing, aka 'pseudo' balancing is not employed in the design, as it would negatively impact upon performance by comparison. 


Is the SSL 2/2+ DC coupled?

The SSL 2/2+ is not DC coupled.

In addition, the monitor pot is passive.


XLR vs TRS Input for Line Level Sources

The XLR input feeds the mic preamp circuit that has increased gain compared to the line input. Without attenuation this will clip the analogue input circuit. Signal sources should therefore be attenuated first or fed to the Line input via the TRS jack as intended. If the source device has an XLR line output an XLRf to 1/4" TRS cable can be used.


Monitor DAW and System Audio Simultaneously

You may wish to disable Windows exclusive mode to hear multiple applications at the same time - instructions are below. Exclusive mode allows applications to take exclusive control the interface so that other apps cannot play sound at the same time. This may cause issues when switching audio apps.

1. Right-click on the speaker icon in the system tray and select Open Sound settings.


3. Select Sound Control Panel.

4. Select the device you want to listen to and click Properties.


5. Under the Advanced tab, uncheck Allow applications to take exclusive control of this device.


6. Click OK to save your device's settings.

After making this change, try playing audio.

The audio should be playing from the selected device.


Mic Input Signal One-Sided on Headphones

If you hear your microphone input on only one side of your headphones it is possible that the stereo switch next to the monitor mix control is enabled. This treats the channel 1 & 2 inputs on SSL 2 / 2+ as a stereo 'Left' and 'Right' input for monitoring.


If you de-select the stereo switch you will hear both input 1 & input 2 as multi-mono sources to both left and right sides of your headphones.


Signal Still Metering with Minimum Gain

High level source signals, including some condenser microphones, may cause meter deflection in your DAW even when the gain pot at it's lowest position.

Mic preamps do not have an off position, so high level signals will always pass through even when no additional gain is applied. You can confirm this by putting a line level source into any preamp.

Additionally, SSL SuperAnalogue preamps have traditionally had anywhere from 12 to 26 dB gain even at their lowest position.


Microphone or Instrument Signal Delay

If you are hearing an audible delay when listening to your microphone / instrument through the headphone or monitor outputs, it is likely that you are hearing the signal after it has been through the DAW. It takes a perceivable amount of milliseconds for signals to get into your computer and back out again. 


The solution is to:

  1. Mute the channel in the DAW that you are recording too (it will still record audio when muted!)
  2. Instead use the MONITOR MIX control to listen to your inputs in your headphones or speakers without a perceivable delay.



When you want to listen back to what you have just recorded, you'll need to un-mute the track you have recorded onto and change the MONITOR MIX level to hear your take. 


Zoom Video Conferencing Support

Zoom supports external audio interfaces on macOS and Windows. Unfortunately, Zoom does not support external audio interfaces on iOS as of this writing October 2020.

If you have trouble with external interfaces on Zoom or other video conferencing apps in iOS, please check with the app developer on if they support external interfaces; many do not.