The 'Vanderpump' reality star got under the spotlight this weekend with his band, The Most Extras, for 2 live gigs where the guys apparently played to packed houses. On Friday, Tom performed at a venue called the Canyon in Montclair, CA ... way out near Pomona.

On Saturday, he did it again ... only this time, him and the band went in the other direction -- again playing at a Canyon establishment, but in Agoura Hills ... which is near Calabasas.

In both instances, TS lost his shirt ... and handled microphone duties bare-chested. He wasn't shy either ... Tom was up there belting out songs like there was no tomorrow, and it sounds like the crowds were rockin' with him for the most part. All in all, pretty good vibes.

Of course, the question some might ask is ... too soon? Clearly not -- the guy was booked, so he has every right to perform ... and it doesn't sound like the cheating hurt sales either.

He's already gone to the reunion and gotten chewed out by everyone under the sun -- both on and off set -- and he's apologized for betraying Ariana Madix. At this point, though ... this saga's been going on a month-plus and there's nothing more to really say. It's over.

AM's reportedly already lined up her next act -- apparently, she's set to appear on 'DWTS' -- and Tom seems set to do the same ... playing his music and running his businesses.