I know the feeling. A few months ago I was experimenting with crossfeed, eventually settled on a custom version that was pretty subtle but made it easier to hear stuff panned hard left or hard right. After a couple days of using it I decided it hurt the detail a bit too much and turned it off. Apparently I didn’t save my settings after turning it off though, because last week I found out I still had crossfeed on. Presumably it got re-enabled next time I restarted my PC and Peace reloaded the profile. I originally experimented with it in May so I’m pretty sure it’s been on that whole time.

Not as big of a difference as mono would be but I still felt like an idiot as soon as I turned it back off. When I originally made my custom commands and did A/B testing I thought I was making a pretty subtle effect, but after months of using it, turning it off felt like getting my ears cleaned out. Huge increase in resolution and the overall presentation/staging feels way more natural. Kinda pissed at myself for taking so long to notice something was wrong.