I read somewhere (dont know if it is true) that the start of the 'red' on analogue meters is the equivalent to -20dB on a digital meter. My previous experience came from recording on cassette decks in my youth where you always wanted to be peaking into the red, but i soon learned to leave plenty of head room on digital levels.
Its a shame digital meters dont start their red at -20dB. it would stop a lot of confusion