As an endurance test, the fifth annual Rock the Bells was a somewhat challenging one. Offering 10 hours of music is a good thing, but when it's in that cold concrete palace by the water, the prospect becomes less inviting.

Grabbing a bite beforehand — to avoid spending large chunks of funds on shabby pizza and french fries — meant missing early sets, The Knux and Slum Village. However, if their sets were anything like that of bellowing Brooklynites M.O.P., they had the typical issues to deal with: a crowd that was still trickling in, blazing sunlight that poured on the hungover, and the not-so-delightful acoustics the Amphitheatre provides for hip-hop. The corpulent duo overcame the obstacles though, their voices in fine form as they ran through songs like "How About  Some Hardcore" and "Ante Up," while charismatically addressing the crowd in between. Amphitheatre staffers seemed unclear on how to deal with the fairly absurd amount of weed smoke in the outdoor venue, but occasional crackdowns did result in ejections.

Host MCs Supernatural, Pete Rock and KRS-One dropped some entertaining freestyles, with Supernatural doing the "give me an item and I will rap about it" routine and the Blastmaser doing his "I will babble for awhile and then launch into any number of slightly reworked first verses from my catalogue" bit. (My favorite KRS-One quote of the night came from a rant in which he both critiqued universities and told the crowd to stay in school — I believe the exact quote was “they want you to play the flute for two years before you get your major!”) An early shout out to Toronto's own Michie Mee paid off when he brought her onstage hours later, explaining that the T-Dot hiphop icon was the first person who met Boogie Down Productions at the airport on their first visit here.

As mentioned earlier, sound was an issue, with reverb seemingly on most of the performers' mics — combined with a concrete slab of venue, and you get a lot of garbled words. And that's pretty much all rappers have to work with. Most of them held it down, though — Slaughterhouse showed a lot of promise, with members Crooked I and Joell Ortiz shining, but the four-piece also had a too-many-cooks vibe to their live show that needs to be worked on. Still, their set was solid, and they have nice T-shirts.  

(Side note: one thing I learned from this concert is that there needs to be a one-year moratorium on MCs yelling "make some noise!!!" at the end of songs. Everybody did it, whether it was during Reflection Eternal's lacklustre set, Big Boi's professional run-through of his side of the OutKast catalogue or an apperance from the face-painted Tech N9ne. At this point, crowds are aware they should make noise.)

RZA showcased verses from his Gravediggaz days, as well as vintage Wu ("Tearz," for one) and solo work like "We Pop," displaying an appeal that nicely offset the schlubbiness of preceding act Talib Kweli. Veterans EPMD also made a nice showing, running through their classic catalogue as if they were being rushed along by the show's packed schedule.

Mos Def may have been the "mos weird" performance on this night, chanting "Michael Jackson" to start, and seeming a touch standoffish as he played tracks from his solid new record The Ecstatic. He didn't connect with the crowd until he brought out Talib Kweli for a couple of songs. Black Star really do work as a unit, commanding both sides of the stage and showcasing the best elements of both artists. Afterward, Mos remained onstage with the DJ, at one point dancing to soul music, without even rapping. Something was off.

One of the biggest surprises of the night was the fact that Damian Marley and Nas actually pulled off their collaboration. Switching between individual sets and duets, it was a thrill watching them trade verses over live versions of Illmatic songs, or the beat for Shyne's "Bad Boys." Nas was at his best when performing songs from the duo's Distant Relatives LP, sounding in-the-moment and not missing a breath. It was Marley who really shined, though, making the stabs at his father's work ("War," "No More Trouble" and a reworked version of "Exodus") feel like something more substantial than mere grave-robbing. After a long, long day, it was this performance that ultimately cemented Rock the Bells as a celebration of hip-hop and summer fun.