Roughly a quarter-century ago, B.B. King said of Joe Bonamassa that "he hasn't even begun to scratch the surface."

It was an undeniable compliment to somebody not yet in his teens, but it was also a challenge - one that the blues-rock guitarist, singer, and songwriter apparently still takes to heart. Bonamassa continually scratches and scratches to get deeper.

His performance April 19 at the Adler Theatre will be one example, featuring a set with his acoustic band and another with his electric - both covering roughly 10 songs. The acoustic sets demonstrate that Bonamassa isn't content to skate by on instrumental virtuosity - unlike too many of his ace-guitarist peers. These shows require solid songs, nuance, and variety.

As he said in a phone interview last week, the two-set engagements are "very challenging vocally and on guitar, because you're essentially switching gears tune to tune."

Even better evidence of his range can be found in his recent discography. In the past two years alone, Bonamassa has put out the Driving Towards the Daylight studio album, live and studio releases with singer Beth Hart, the third and final album from the Black Country Communion super-group, a studio disc by the jazz-fusion Rock Candy Funk Party, Beacon Theatre: Live From New York, the live album An Acoustic Evening at the Vienna Opera House, and the four-disc Tour de Force: Live in London - documenting themed shows at four venues with different band lineups and more than 60 different songs. And he has a new studio album planned for fall release. (The old saw about the weather can be adapted for Bonamassa: If you don't like his latest record, just wait a few minutes.)

From an Adler Theatre stage filled with more than 200 musicians, the Quad City Symphony forcefully premiered Gustav Mahler's monumental Symphony No. 3 on April 5. Moving from the dissonance of uncertainty to the transcendental climatic moments of harmonic resolution, the concert was abundant in gravitas, contrasts, and drama that revealed a thorough artistic vision from Music Director and Conductor Mark Russell Smith and included a valuable collaborative process with other area musical organizations.

For all of about six seconds, the Quad Cities band Bedroom Shrine's new album No Déjà Vu seems content to set a mood.

The first sound on "Brown Recluse" is the whirring of a tape machine, whose unsteadiness makes the opening notes of acoustic guitar tremble plaintively.

But before that old-time folk vibe can register, the wind chimes tinkle softly, leading to some gentle feedback that builds to the simultaneous entrance (at the 19-second mark) of hand claps and electric slide guitar. Those two elements pull against each other, the hand claps establishing a pleasant groove with the acoustic guitar while the slide concisely articulates its grudge.

The instrumental is clearly meant as a table-setter, but it illustrates that Bedroom Shrine has no interest in dawdling. At all of 85 seconds, the track musically sketches out the band's Facebook blurb of "rock 'n' roll gets lonesome" and scurries off.

That's the basic method of the album, whose 12 songs run a total of 32 minutes. That by itself means nothing, but it relates to both the album's charm and its shortcoming: The vivid, sharply drawn songs leave you wanting more (good!), but they also feel like sketches that would be even better given the time and space to grow into more-mature form (less good!). It's telling that the only two songs that run more than three minutes - "You're Gonna Lose" and the title track - feel most like they've reached the ends of their natural lives.

Blake Selby understands that he's already at a disadvantage.

"Look, there are a few facts," he said in a phone interview this week. "Number one, I'm white and I'm in the rap game. ... I'm already fighting an uphill battle. ... The other thing is that I'm not from the streets. I never claim to be; I never pretend to be in my raps. ... This is kind of my way of fighting back."

"This" is his first full-length album, Ammunition. The Quad Cities-based hip-hop artist (who also owns Quad Cities Fitness in Bettendorf) has a record-release show Saturday at The Clubhouse in Bettendorf, and the album and show represent his musical introduction to his new community.

As the name suggests, it's no clammy handshake. The 16-track album is loaded with aggressive, surgical-jackhammer rapping. It features the Chicago hip-hop artist Twista and singer Sam Kay on "Never Let Go." It brings along the Quad Cities metal outfit 3 Years Hollow on "Monsta." And its straightforward production (by The Chemist) mainlines the hooks.