Love Triple Crown! While in college at Texas State, I discovered & became a regular here.  I recently moved to Kyle & am now re-discovering this gem of a dive bar. Located off the beaten path from the (fraternity ridden) courthouse square, Triple Crown has Cheap drink specials & friendly bartenders who still know your name. The theme screams "dive bar" but in a good way, & Triple Crown was formerly a massage parlour proudly displaying the former sign in the back behind the pool tables. The big  covered patio outside is very nice & a welcoming destination from the smoke-filled inside during busy nights (San Marcos still allows smoking in bars/restaurants).
Triple Crown boasts themselves as being the "live music capitol of San Marcos" with live music almost nightly & a rather entertaining Open Mic night on sundays featuring Steve n Steve amongst other local talent.
The other live acts are hit & miss, & alot of local talent play or have played shows here. Be prepared to pay a cover charge during a live show (cover charges vary depending on the venue).
So whether you live close to or far from San Marcos, it's well worth checking out Triple Crown!