I received a tender document which calls for the supply of DI units which can handle an input signal of +50dBu.
I can't imagine a situation where you would ever want to deliver mains voltage to a DI, but, I'm not a consultant.
andy
Do they give a representative model number?
Sometimes people specify products that are not made. Sometimes to weed out people who don't understand.
I had one case years ago in which I got the job, simply because I called and questioned the spec.
The "designer" said that I was the only person who understood how crazy the spec was, and called to question.
Others just overlooked it and didn't care.
Kinda like brown M&Ms on the staging rider