Ableton Utility is your friend.

Ableton Utility

While the Utility audio effect might not look like much, it should be the compound that holds your mix together as you progress through a large session. Giving you the option for additional gain staging that is flexible and lightweight, there's no reason to not use it! 

​The Importance of Gain Matching
Output gain is such a key essential part to mixing due to gain matching after processing. If you have ever had a chance to speak with experienced mix engineers, they will always tell you that the rough mix is very important. The reason being that it sets the layout of how your mix will turn out in the end. With proper gain matching, this ensures that there will be less major changes, and more focus on fine tuning during the final stages. This introduces the reason why the Utility is so essential. 

In my template, I have a Utility plugin on almost all of my groups and subgroups. I'll often find myself gain matching the processing of a plugin with the Utility more than the built in output gain of the plugin. Some plugins don't allow the fine tuning of their output or makeup gain to the hundredth, and that's where Utility shines. Another great use for gain matching is to group (CMD+G or CTRL+G) a plugin with a Utility into an Audio Effect Rack. Doing so allows full control over bypassing the enclosed effects at the same time or even adjusting the overall level of the effects!  

Audio Effect Rack

​The Secret to Mono in Ableton
If you have used any other DAW and compared it to Ableton, you will find that Live does a lot of things out of norm. The exclusion of mono audio tracks would be one of them. But the good folks at Ableton didn't leave that key element out completely, they just tucked it away in an easy to find Utility preset titled "Mono.adv" under the Utility dropdown menu. Here is a direct quote on this subject from the Ableton manual: 

"​The Width control acts as a continuous mono to stereo controller when set from 0 to 100 percent."

Disclaimer: Now there has been speculation on just using the dropdown menu to select the Left or Right channel of the source to create the mono signal, but I myself feel safer using Ableton's preset since I feel they would be correct. Although the theory makes sense, but if you have any more information on this or would like to discuss, please leave me a comment. 

When using the preset, you will notice that the Width parameter is set to '0.0%' with no additional changes, thus converting your signal into mono. This helps greatly with maintaining the integrity of your mix. In a recording environment, the majority of live instruments are recorded through mono signals into the console and summed. Whether you're mixing live instruments or mixing electronic instruments inside the box, those general elements should always be considered. 

Opinion: I will say that after using the Mono Utility plugin for a while, I decided to do a comparison to see if there was any integrity or gain loss when converting the signal into mono. In my personal experience, I noticed about a 0.5dB loss in the signal whenever the plugin was applied. So I have created another mono Utility preset that gives me that 0.5dB back. Again, if you have any other studies on this subject, please let me know in the comments. 

My Mono Utility

Additional Features and Conclusion
There are also other functions to the Utility, like an independent Mute, a DC Filter (filters out DC offsets and extremely low frequencies that are far below the audible range), and also two Phase controls. While this Utility might not look like much, it is packing some key ingredients to mixing in Ableton Live. So don't go pushing this essential tool off to the side, because it's only there to help your mixes progress to the next level in Live! ​

Mix Chain