What do you use to check for brightness?

I'll post this in computer audio because that's what I'm dealing with, although it applies more broadly. Sometimes tonal brightness is obvious, even painful. But most of the time it's more subtle and too easy to get used to; i.e., where "I just know" might not be so reliable. Do you have any recordings, music files or online audio sites that you fall back on, where you know that if a system sounds like such and such, it says "bright?"