Misconnected interconnect

I took my system apart the other day, and in putting it together I temporarily attached one interconnect from the cd player to the single-ended OUTPUT of the preamp, rather than to the single-ended INPUT.

Fortunately, I discovered the error before I played any music.

The preamp and cd player were both powered at the time (ie, both were "on," but not otherwise in use).

My question is whether what I did could have damaged any of the circuits. Ie, despite not having played any music, is it possible that a brief mis-connection in this way caused damage to any of the circuits. (Assume "standard" forms of wiring, if there is such a thing.)