For eight years Hot Buttered Rum String Band (HBRSB) has refined its Newgrass sound to incorporate an amalgamation of styles and genres. Based around the traditional acoustic string set-up (and with the somewhat recent addition of a drummer), HBRSB paints on a bluegrass canvas with a folk, rock, reggae and jazz palette. And while the band owes a nod to contemporaries like String Cheese Incident and Leftover Salmon, HBRSB took that “Colorado sound” and made its own brand of Northern California string stew. Much like its Colorado brethren, HBRSB earned a devoted following by way of relentless touring and ever-changing set lists. The band is a veteran on the festival circuit, having played memorable sets at Telluride Bluegrass Festival, Newport Folk Festival, SXSW, High Sierra Music Festival, Bonnaroo and San Francisco’s own Hardly Strictly Bluegrass. Along with sometimes humorous ditties, the band puts a premium on solid, original songwriting and instrumental excellence. Their musical prowess has been noted by many fellow musicians and the band has had the opportunity to share the stage with the likes of The Grateful Dead’s Phil Lesh, Ben Harper, Peter Rowan and banjo innovator Béla Fleck. “I’ve always had huge aspirations for this group,” says guitarist Nat Keefe. “But then, you know, I also have these moments of introspection and I can’t believe how well it all came together. The best part for me is the connections with fans and friends, meeting people who’ve connected with our music. Another highlight for me is that someone named their baby after my song ‘Amanda Lynn.’” While HBRSB made a name as a hard-driving, pistol-picking string band, when Keefe and crew added a drummer a couple of years back they were able to keep that driving, pulsing string band energy and propel the sound even further. While string band purists may scoff at the notion of adding a drummer, the percussive addition is merely a return to where it began for HBRSB, and serves to add an intensity and force to the band’s sound. “The first incarnation of Hot Buttered Rum years ago had a drummer,” says Keefe, while the band prepares for a show in Las Vegas. “Then we became the string band quintet that most people are probably familiar with. Then when Zach [Matthews] left in November 2008 we found ourselves at a crossroads. That’s when we decided to add a drummer. It’s funny, but in some ways we play more bluegrass than we did before. It allows us to have a bigger sound than before. Now, we’ll have these quiet moments like when we do an old time country duet and then when you bring in the drums on the next song it just sounds so much bigger.” For the current tour however, Keefe, Aaron Redner (mandolin, fiddle) and Eric Yates (banjo) are performing as the stripped down Hot Buttered Rum Trio. The return to focusing on just strings forced the band to step up its picking and focus more on vocals. And while the rollicking energy is still more than prevalent with the trio, the toned-down sound allows for more nuanced strings and forces the players to re-imagine many of the band’s classic standards. “I like stripped down music,” Keefe says. “I like playing quieter music sometimes. We’re basically doing this because it’s fun and a challenge but also because our bass player Bryan [Horne] had a baby. The quintet just can’t do 200 shows a year like it used to. I’ve really been impressed with how much we make people dance without the drums and bass. We played in Madison a couple of nights ago and the place was just rocking. But doing this trio is what we needed for the next stage of our growth. We’re becoming better players and better singers and then we bring that back to the quintet and it really helps.” Hot Buttered Rum Acoustic Trio plays The Waiting Room, 6212 Maple St., Saturday, Dec. 11, at 9 p.m. Tickets are $10 ADV/$12 DOS; available via radkadillac.com.