Yes, STEREOS is a Scrabble word!

Letter values in Scrabble US: S 1, T 1, E 1, R 1, E 1, O 1, S 1.

Is it a valid word?

STEREOS is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

reproducer in which two microphones feed two or more loudspeakers to give a three-dimensional effect to the sound
two photographs taken from slightly different angles that appear three-dimensional when viewed together

Also: stereo system, stereophonic system, stereoscopic picture, stereoscopic photograph.