LIVE Recording Hum -Tape Out - Mackie

[MNAirHead]

Question.

Application - Church Recording
Recording a reference recording of a church service

Quest - simplification
I'm trying to simplify a setup that used to include a mac, protools, MAudio interface etc.

Since this is not multi track and has a shelf life of just a few weeks, it makes sense to simplify

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Normal Setup
I normally send a signal from one of the mains (on a stereo board) or from a sub... (I have also tried a Lexicon USB interface with acceptable signal to noise)

Chain... 1/4&1/8 cord - laptop mike in - audacity.

I just tested tape out (RCA&1/8 cord - laptop mike in - aucacity) ..

Problem is I get hum with this setup.

Question -- is signal/noise just a characteristic to tape out OR am I doing something wrong?

Any experience and coaching appreciated.