I just bought 3 pairs of polks a few days ago:
here is the issue...the 4s have a sda pug! refer to the pics. one speaker also has a selector switch. there is also no serial#. i checked all the vintage polk sites i could find, and saw NO monitor 4s like this.
if i am making a big stink about nothing, let me know, otherwise please shed some light on this for me.