Measurements complete.

With both inputs grounded and the switch in Phono I'm getting the noise floor at about -66dB.

Same config with the switch in Line the noise floor DROPS to about -78dB.

These are peak levels. RMS levels are less which get you close to the spec in the datasheet in the Line position.

Zooming in reveals that the noise in the Line setting is pretty much all 60Hz noise.

I'm happy with this performance for what I do.