With much of musical Philly in dusty Texas for the annual South by Southwest fest, it's only fair that we had the Lone Star State's fattest calf - the toast of Houston, ZZ Top - on righteous display Saturday, and in an intimate setting to boot, the Electric Factory. That it happened to be the same evening Philly, Irish or not, was celebrating St. Patrick's Day only made the sold-out show's throng rowdier and ever more Erin Go Braghish. That's an atmosphere just ripe for a ZZ Top party.

The trio - blues-rock-turned-electro-dance-pop-and-back-again - has been around since 1970, so Billy Gibbons (guitar), Dusty Hill (bass), and Frank Beard (drums) had their rough routine down cold. Beards long (at least Gibbons' and Hill's), sunglasses up, hats on, there was a sixth sense among them as they (just barely) compressed their arena-rock roar into a chewy, bite-size, dirty blues squeal.

It made perfect sense that they would come to do a sludgy cover of Jimi Hendrix's "Foxy Lady" - much of the night's initial cuts were curt, rangy takes on Hendrixian, psychedelic saturated blues with a nasal-voiced Gibbons singing through "Got Me Under Pressure" and "Jesus Just Left Chicago."

The addition of the frank, funky blues of "My Head's in Mississippi" was just gooey icing on a bittersweet cake, especially considering that what makes ZZ Top's three-chord-classics blissful is that they add a little Tejas spice and smoke to each guitar lick and rugged rhythm, then splice Hill's harmony vocals into the dense blues batter.

Songs from 2012's La Futura - the clucking "Chartreuse" and the murky "I Gotsta Get Paid" - were slathered in that hot sauce, while "Flyin' High" reminded fans of their '80s arena-rocking cool and MTV-era gloss. So did Gibbons' and Hill's side-shuffling stroll, stringed instruments covered in white fur, and their fleet, syncopated version of "Legs."

By the time they hit the crusty "I'm Bad, I'm Nationwide," they were off to the dirty-boogie usual of their past, a tone that, like its chugging locomotion (heard loudest on "Cheap Sunglasses" and a smooth "Gimme All Your Lovin"), is its signature.

With Beard hunched over his double-bass drum kit, punching his toms and riding the rims of his snare for the dirtball classic "La Grange," Gibbons' voice lowered for the cut's familiar cackle, leaving vocalist Hill to take control of the mike for the torrid closing boogie of "Tush."