quadraphonic system vs quadraphony

quadraphonic system and quadraphony both are nouns.

Word	Noun	Adjective	Verb	Adverb
quadraphonic system	Yes	No	No	No
quadraphony	Yes	No	No	No

As nouns, quadraphonic system and quadraphony are synonyms defined as:

quadraphonic system and quadraphony: a stereophonic sound recording or reproducing system using four separate channels

Other synonyms of quadraphonic system include quadriphonic system.

quadraphonic system (noun)	quadraphony (noun)
a stereophonic sound recording or reproducing system using four separate channels	a stereophonic sound recording or reproducing system using four separate channels