Indeed, Rush is amazing. Like you, I also lost interest in them once they went with synthesizers. It was the Digital Era and disco may have had some influence too. Rush wasn't the only band to fall from grace though.
{Many of my favorite bands took a bad turn in the 80's. Some of them even suffered the tragic loss of some key members during this time. (ie. Cliff Burton of Metallica and Bon Scott of AC/DC [although Brian Johnson was pretty good too], RIP. David Lee Roth didn't die, but Van Halen just wasn't the same without him.)}
Anyways, I leave you with a true Rush classic.
Rush - 2112 [HD FULL SONG]