power plug for Technics SX-K450

I purchased this from my local goodwill store for $6.88 it did NOT come with a cord, straight AC in. I noticed a small keyway at the bottom of the socket, I have an AC cord that fits,although the cord does not have a keyway and is smaller it fits either way, my concern is not having the proper cord,is the keyway there to prevent plugging it in the wrong way and is this polarized? I don't want to let the magic smoke out that makes things work LOL thanks in advance, and thank you for allowing me in the group.

Hi
AC power (2 pins) should work either way, because it's not polarized as DC is.
What powertype in to the KN should be readable at the back at the KN where the plug insert is placed.
DC often have a smaller round plug, where current voltage and plug polarity is marked at the insertion point.