"It wasn't really sounding like what I was hearing," offered Brenner, a 39-year-old with dark hair, a face marked by stubble and thick black glasses perched on the end of his nose. To better replicate the music that was consuming him, he began looking beyond rock eight years ago, searching for an instrument that could match the type of sound rattling around in his head.
It led him all the way to country-music influenced bluegrass, a genre that relies heavily on an instrument called the lap steel guitar. It may look like a regular guitar, but the musician plays sitting down, sliding his hands across the strings while the instrument faces upward.
"It has a vocal quality," said the Center City native in a relaxed voice. "I'm not the greatest singer, but I felt like I could get my singing vibe out of playing lap steel. There's something pure about it."
He began lending his new style to other bands. He opened for Sinead O'Conner, Pete Townshend, Ziggy Marley and the Melody Makers, and even performed on stage with Bruce Springsteen. He has also done some soundtrack work, creating background music for the failed ABC-TV series, "Push, Nevada."
Since then, he's gone solo, and his newest album "My Buzz Comes Back," took nearly five years to finish. It features Brenner's smooth slide guitar with rapper Mic Wrecka, lending the album a vibe indicative of South Philly's instrumentally-based hip-hop band, The Roots.
After recording the title track back in 2001, Brenner knew he was on to something good.
"I wound up digging that track so much that I kept thinking, if I could put a whole record together like this, it would be really cool; it'd be something that I hadn't done before," he said.
Brenner lives with his girlfriend of 10 years in Philadelphia's budding hipster capital of Fishtown. He plans to hold a record-release party on Sept. 10 at the Fire Philadelphia Bar and Grille, a couple of blocks from his house, and expects to sell out the roughly 150-person venue.
Brenner generally dresses casually, but on stage at the Fire, he should be wearing his signature white suit with black tie and black handkerchief in his pocket - and dark sunglasses.
So, what's with the nickname?
"In high school, this guy used to tease me on the basketball court because I was so slow. He started calling me 'Slo-Mo.'
"I made the mistake of telling these guys years later at my first gig as a steel player. I was playing with this country duo, cross-dressing guys from New York. Everyone had nicknames like Cousin Rob - they nicknamed me Cousin Slo-Mo."
He eventually dropped the "Cousin" part.
Brenner, who had his Bar Mitzvah at Society Hill Synagogue, admits that life on tour for a good portion of the year doesn't quite lead itself to regular synagogue attendance. But he does identify: "I'm very culturally Jewish. I'm constantly following what's going on in Israel and [with] Jewish issues."
As for the future, Brenner recently returned from a tour of the United States and Canada, and wouldn't mind a respite.
"I'm interested in getting a local profile," he acknowledged. "Sometimes, the idea of touring is futile. It's just such a big country. [And] I hate staying away from my girlfriend."