A summing amplifier simply sums multiple audio streams to stereo, while the DAW's mixer is used to perform the mixing functions of balancing and panning. ... To put it simply, if it has level controls and/or pan pots on the inputs it is a line mixer, not a summing mixer.

What is a summing device?

The summing function allows you to combine multiple input signals to the main channel output. It is typically most used when connecting to a factory system that has dedicated outputs for just the highs and mids. You can use the summing function to sum those signals to create a full range output.

Do I need a summing plugin?

If you're using LUNA, Universal Audio's comprehensive recording system, then the Neve Summing extension is a must-have. ... This extension integrates right into LUNA's mixer, making it easy to inject analog attitude into your mix without complicating your workflow.