With the Headrush Prime's release, it's become very popular to channel an alternate output, your mic, or a second guitar to a separate output for use. Some users have experienced that in doing so, their XLR outputs come out louder than their 1/4 inch. They'll check the audio settings and see that the 1/4 inch output is appropriately set to Line, and their board itself does not have separate EQ controls between those outputs except the output controls on the signal path.

Nothing is wrong in this scenario. Your XLR's are speaker cables, and I'm willing to bet your 1/4 inch cables are just regular guitar/instrument TS cables. Nothing wrong with using them occasionally, but instrument cables use a thinner gauge wire with a lot of shielding; and in the simplest terms it's just carrying less signal out. Which may be okay for practice scenarios. It has to do that for your instruments because the low voltage signal running through it from an instrument is more sensitive and needs a lot of buffer to be protected. However, in full live performances we do suggest not using them because eventually you'll notice that your instrument cable connector is hot- that's the extra signal not being sent is coming off as heat, and eventually it will begin to break down your cable.

What you need to look into is 1/4 inch TRS Speaker cables. They're essentially the same gauge as your XLR cables, but they use the 1/4 connector. Speaker cables run a lot more signal, and as a result signal getting into them gets drowned and canceled out easily. Don't use them for your guitar connection itself, but feel free to give a good set of TRS cables a go for any scenario that you are using the 1/4 inch out.