God's agency and ears in preaching

Most of us who preach are aware of the terrifying reality that God may speak through our words. As we get up to preach, our hope and prayer is that God may use our unclean lips to speak. It is a strange and genuinely humbling thought, though eventually we come to be comfortable with the idea of shared divine and human agency in preaching as we speak to our congregations.

Reading Hebrews 1:8 I was struck by an even scarier thought

"But unto the Son he says "Your throne O God, is forever and ever"

God speaks through David (psalm 45), not simply to the people of Israel or Christian congregations, but to his Son.
How scary is preaching if we conceive it this way. That the Father might speak to the Son through us.
The idea of 'preaching to an audience of one' is sometimes bandied about, though usually simply meaning 'careful what you say because God is listening. But is it dodgy to say that our preaching may be caught up into the divine conversation, of the Father saying 'I give you these people' and the Son's reply, 'I hand them back.'

Scary