For touring musicians, the Forum offers elegantly decorated dressing rooms rather than converted locker rooms that serve the purpose in many sports arenas.

Plus, there are no glassed-in luxury skyboxes that reflect sound in sometimes cacophonous ways during concerts, and which also put fans in the top rows significantly farther away from the musicians onstage.

For musicians, that means a large-scale room created to enhance the sound of their music, a luxury noted during the show by Eagles founding member, singer and songwriter Glenn Frey.

"This is the best-sounding room of this size in the world now — take my word for it," Frey said.

PHOTOS: The Forum, renovated

Frey and his longtime band mates have reason to know, given the numerous times they've toured the world. But they are also not disinterested observers: Their longtime manager, Irving Azoff, is now partners with MSG Co. with his latest business venture, Azoff Music Management.

Another improvement is the seats. Red upholstered high-backed chairs have replaced the yellow hard plastic arena seats. And above it all, the Forum's upper reaches feature a blanket of pinpoint lights that create the impression of a starry night. No more electronic scoreboards and basketball backboards hoisted into the rafters during concerts.

"It's comfortable and it's beautiful," Heidi Griffith, 40, said, standing with her friend, Karen Pene, 46, both of Chatsworth, on the arena's new outdoor plaza, where many patrons stepped outside during intermission to have a smoke or drink. "I can't believe it — I have a client who used to use the Forum for storage. It's amazing."

Therese Cron drove down from San Luis Obispo to catch the show with her brother Ted Gillan, who came up from San Diego.

"I saw so many great acts here," she said. "Jackson Browne, Linda Ronstadt.... What was the band with the guy who played flute? Jethro Tull! The Doobies. And the Lakers."

MEMORIES: Readers' remember their favorite forum shows

Madison Square Garden Co. spent $100 million to buy and refit the Forum, hoping to compete with Staples for the top-grossing entertainers by offering what the downtown sports arena can't: the world's largest indoor theater designed specifically with music in mind.

It's a gamble given that the Forum — once home to the Los Angeles Lakers and Kings — will feature no resident sports teams.

In addition to the Eagles, other acts scheduled to play the Forum in coming weeks include pop crooner Justin Timberlake, rock band Imagine Dragons and electronic dance music DJ Armin Van Buuren.

The Forum's glory days are on display via life-size photos on walls throughout the arena of dozens of rock, pop, R&B and country acts that played the building during its three-decade reign.

Its future, however, now rides predominantly on the caliber of musicians who will be coming through. MSG's challenge in its first West Coast venture is to fill the calendar and turn a profit without the slate of guaranteed crowds that sports teams bring.

The potential benefit is a building without the compromises inherent in a multipurpose facility serving very different agendas.

"It's still the same old Forum," said Barrie Wellman of Lake Forest, a veteran concert-goer who reminisced with his brother, Brian, about the dozens of concerts they attended at the Forum in the 1970s and '80s. "Lines are long and you can't get through the concourse during intermission.

"But they've done pretty much everything they promised: It's gorgeous, the sound is outstanding and it feels pretty intimate," Wellman said.

randy.lewis@latimes.com