Broken Social Scene is a little like the Wu-Tang Clan of indie rock -- you never know who is going to be on board.

The Toronto-based collective can roll with a core of six members or bulk up to an ensemble as large as 11 or 12. When the band plays the Byham on Wednesday it will be eight members strong, with the option of a pick-up local horn section or the occasional appearance by Tortoise/Sea and Cake drummer John McEntire.

Regardless of the size, the constant is that the sound will be epic, multi-textured and freewheeling, ranging from jazzy ambient rock to noisy Sonic-Youth-like outbursts.

"Being a drummer in this band," says drummer Justin Peroff, "especially in a live setting, involves communicating with a lot of different elements of the music and a lot of different musicians, and a lot of them being guitar players. It's really just sort of anchoring controlled chaos ... it's like a big playground that just has to be operated properly, but, at the end of the day, it's super fun. Just a bunch of friends playing music together."

Broken Social Scene started in 1999 with singer-guitarist Kevin Drew and bassist Brendan Canning, who emerged two years later with an atmospheric debut featuring numerous contributors, including Mr. Peroff, Leslie Feist (aka Feist), Charles Spearin (Do Make Say Think), and Evan Cranley of Stars. The sprawling live show would further enlist the likes of Emily Haines (Metric) and Andrew Whiteman (Apostle of Hustle).

A second, more pop-focused album, "You Forgot It in People," rose to the level of indie classic, scoring a 9.2 on Pitchfork and winning the 2003 Juno Award for Alternative Album. The band followed with a self-titled album in 2005, and then took a hiatus around 2007 to allow the members to work on other projects, including the frontman's notable "Broken Social Scene presents Kevin Drew" album. The drummer says there was never a doubt about the band re-assembling.

"This band has never been in absolute risk or danger zone of actually falling apart and disbanding. But like any band you are ultimately in a relationship, and a relationship of many dynamics. We've all known each other for a long time and some of us have been playing music together for well over a decade. Some of us have known each other for over 15 years. I think at any time, in order to save something from falling apart, you just have to give each other a big hug and walk away for a while."

With various side projects -- or main projects, depending on how you look at it -- settled, the Broken Social Scene regrouped last spring to work on a fourth album, "Forgiveness Rock Record," with producer Entire, highly regarded as a post-rock pioneer.

"Kevin e-mailed him regarding a remix actually for his solo record and John responded saying that he doesn't really do remixes anymore," Mr. Peroff says. "Myself and Kevin and Charlie are such huge dorks for that guy that we were excited that he even replied to that e-mail."

They paid a visit to his Chicago studio for a day of recording that went so well, it led to a full-blown project, the first for Broken Social Scene outside of Toronto. The drummer said it helped sharpen the band's focus.

"We woke up in the morning and we knew what we were there to do. When you record in your own city, you're very quick to get distracted by anything and everything."

The result, "Forgiveness Rock Record," is yet another acclaimed album for Broken Social Scene and one that's been called its most song-based record.

"I would compare it more to 'You Forget It in People' than the self-titled record," the drummer says. "There's a lot more ethereal and textural stuff happening on the self-titled record, and it's a lot longer and a little more experimental in parts. But [this one] is not a Dave Newfeld production, so that's where it contrasts and that element of the record might be a little shocking to some."

While being a darling of the indie is certainly the goal of many bands, it does come with the pressure of having to push the boundaries each time for a fanbase and critical base that isn't always quick to forgive.

"I try not to think about that stuff," Mr. Peroff says. "At the end of the day, you do want to please people through music, but there's an aspect of making music that is self-satisfying. We all picked up instruments and started to play them with friends because we wanted to. We liked the way it felt and sounded. Now there's another element that has been introduced, which is fans and media listening very closely. I don't think it really effects us as a whole while we're creating. I never once heard murmurings of 'Well, I don't know if this is going to manage to get five stars in Rolling Stone.' "

Critics Andrew Druckenbrod and Scott Mervis talk about music on "The Beat," available exclusively at PG+, a members-only web site of the Pittsburgh Post-Gazette. Our introduction to PG+ gives you all the details.