This applies to the Scarlett and Saffire Ranges
When using Zero Latency monitoring (sometimes referred to as direct monitoring) it's possible to hear the input signal twice, once through zero latency monitoring and a delayed version of the input signal through your DAW. This leads to hearing an echo, or a signal with phase issues.
To avoid this issue when using zero latency monitoring to monitor your input channels, you should mute the input channels in your DAW. This will not prevent the audio from recording, it just means that you will only hear the zero latency signal. To listen back to the signal once recorded, unmute the channels.
Some DAWs may have a global setting for deactivating software input monitoring to save the need for you muting each channel when it is record enabled.