When running sound for a group with keyboards and other devices that have balanced outs, I will often run them through the same snake and attach them to the line level input on my mixer. I don't generally use a DI box in cases like this, unless dealing with a DJ mixer or something that doesn't have balanced outs.
I was once told that I should use a DI box for everything line level, rather than using my method, to avoid impedance issues with long cable runs.
I don't really understand this reasoning. Is it true? And if so, can you help me understand it?
If it is true, then why isn't it an issue for setups with a dedciated monitor mixer, and line-level direct outs going to FoH?