My iMac's songs play for ~8 seconds and stop.

The 8 second song drop was happening whether attempting to play a downloaded song or a streaming song. It turns out the culprit was my computer searching for the Bose Mini speaker it was no longer paired to. I guess the search stops after 8 seconds? Apparently, my placing the speaker on its charging base disconnected the Bluetooth pairing. The iMac should have automatically reverted to its internal speaker, but for some reason it didn't. Funny, though, that a song would play via the iMac's internal speaker for 8 seconds. Perhaps a pairing problem notification message is supposed to pop up on screen at the 8 second point? Regardless, I rectified the 8 second playback problem by selecting the iMac's "Settings" icon, "Sounds" submenu, and there choosing the internal speaker option. And when I once again paired the (now charged) Bose external speaker with the iMac, all songs played normally. Just some weird anomaly I had never experienced in the two years I have used this Bose Mini speaker. Hope this information is helpful to anyone experiencing a similar circumstance, but then again I hope nobody ever does--It's scary to think your entire music library may be corrupted!