Performance sound quality reflects how accurately a recording reproduces the original sound. It is influenced by recording, production, mastering, file format, and playback equipment.
It helps to think of it as a chain: the original master, the file you obtained, your software and gain staging, the mixer, the sound system, and finally the room itself. The chain is only as good as its worst link, which is why chasing lossless files while running the mixer into clipping is effort spent in the wrong place. A true 320 kbps file played at sensible levels will beat a lossless file pushed too hard every single time.
The part actually under your control on the night is narrower than it feels. You cannot fix a badly mastered track, a poorly tuned system, or a room with difficult acoustics. You can control what you bring and how you level it, so filtering out low quality files during preparation and leaving yourself headroom in the booth are the two habits that make the most audible difference.