After three transfixing selections of Scandinavian art-metal before a rapt Electric Factory crowd on Wednesday, Mikael Åkerfeldt, the mustached singer-guitarist-composer for the Swedish band Opeth, delivered some spot-on if understated banter: "As usual, we don't have much to offer other than five middle-aged guys playing rock, dazzling displays of lights, and a good sound."

In 11 studio albums over nearly 25 years, Opeth has offered perhaps the most fascinating evolution in global hard rock. In their seven-song set, they showcased their ability to build off the blistering yet precise power of Swedish death-metal, while incorporating prog-rock sophistication, acoustic guitar passages, and sumptuous keyboards. "Forest-metal," they've been called.

Flanked by nimble-fingered guitarist Fredrik Åkesson and Uruguayan-born bass virtuoso Martín Méndez, Åkerfeldt led the quintet through new and old. That included the chugging yet ornate "Cusp of Eternity" from this year's Pale Communion and a moody read of "The Moor" from their 1999 album Still Life. The flourishes of Legolas lookalike Joakim Svalberg on mellotron and Nord Electro 3 keyboard situated Opeth as the Yes or King Crimson of modern dark metal. Åkerfeldt alternated between soaring/harmonizing vocals to his guttural "death growl" roots, helping to reassert the band's singular identity.

Earlier, fellow Swedish metal vets In Flames had reeled off 15 songs in their coheadlining set. This Gothenburg-based five-piece band has many parallels with Opeth. They also began in 1990. They've also made 11 albums, the latest being Siren Charms. And like Opeth, they have grown from a base of invigorating, extreme hard rock (sometimes called "Swedecore") to produce complex music (dubbed "melodeath" for its marriage of melody and death-metal).

In their 75-minute set, lead singer Anders Fridén and company exhibited a thrashy aesthetic, shifting from smooth singing to extended, high-energy power-yowls. Newest member Niclas Engelin combined with Björn Gelotte for some dizzying dual-guitar work.

Red Fang did a deeply satisfying half-hour opening set but was and is, literally, a world apart. The scruffy, no-frills quartet hails from Portland, Ore. A key band on the roster of Philly's own Relapse Records, Red Fang has shown serious chops, riffs, and tunes on its three albums, along with an appealing have-fun, quasi-parodic party-metal attitude that came through onstage, propelled by alternating vocalists Aaron Beam (bass) and Bryan Giles (guitar). Red Fang's gloriously goofball videos remain a must, starting with the low-budget Monty Python homage "Prehistoric Dog," its concluding song Wednesday.