https://www.youtube.com/watch?v=tPBitFrmlzo
The video was very helpful. To have a truly balanced component, it needs to have 2 completely identical circuits that are out of phase (full deferential). OCD HiFi Guy also said true balanced components do not have RCA connectors, only XLR.
My source is an Eversolo DMP-A6 which at $850 most likely is not balanced even though it has XLR outputs. My preamp and amp are MacIntosh C2300 and MC 302. While they are more expensive, I am doubtful they are fully deferential, and they both have RCA connectors.
I will, however, call the companies and report back. At the end of the day, it doesn't sound like XLR versus RCA for my system will make a significant difference.