I’m as guilty as anyone of letting my player sounds and vocal effects creep up if unattended for long! This is why I strap a pocket digital recorder (I like my Zoom H4n) on my headphone outputs if I’m not using them, and just roll on record most of the time, whether rehearsing or performing.. I find it next to impossible to be super accurate about levels while I’m actually playing - I can get in the ballpark but to truly judge if I got it right requires me to listen critically to the playback. Then it’s a snap to hear whether any player part is too far forward or backwards, whether the effects match the backing (another common mistake) and if my voice sits in the track correctly. Play, record, listen, adjust. Rinse and repeat a couple of times or three, it gets on the money! Sure, eventually you get an ear for what’s going to be close, but ‘perfection’ (whatever THAT is!) always takes a few goes before it’s good. Digital recorders are an arranger player’s greatest asset after the keyboard itself…!