So he’s doing it for the money.

And, oh, why not? Bassist John Entwistle has plenty of ways to scratch his musical itches, and if hitting the road with the Who means he can make a little dough while he’s doing it, well, good thing.

“When you’ve got a big house and a studio to support, you have to go out and work,” says Entwistle, 52.

“You can’t afford to sit on your bum and say, ‘What a great career.’ ”

Along with a large supporting ensemble that includes Billy Idol, Gary Glitter and a full brass section, the Who’s surviving members — Entwistle, Roger Daltrey and Pete Townshend — pile into the Palace of Auburn Hills tonight to roll out “Quadrophenia,” the band’s long-neglected 1973 rock opera.

The big stage production takes its cues from a six-show summer stint at Madison Square Garden, whose success spurred this U.S. sprint.

“We didn’t make anywhere near as much money as people thought we did,” recalls Entwistle, who says the group’s sporadic touring in the ’70s, along with England’s searing income tax and a few bad investments, left members without the financial reward you’d expect for one of rock’s A-list acts.

No word on where the Who goes when this tour wraps up in late November — a new album and tour for ’97 have been discussed — but it is certain that some rock purists don’t like where the group has been the last few years.

The question is a tired one, lurking at least since the group’s lush and glittery 1989 tour, and, for some fans, since the 1978 death of drummer Keith Moon: Is the Who selling out?

Entwistle concedes that the Who, the band that defined guts-to-the-wall rock ’n’ roll in the late ’60s, isn’t the same group anymore.

“This Broadway kind of thing wasn’t the Who,” he says. “It’s fine. If that’s where the Who are now, that’s where I am.”

Anyway, if Entwistle feels like really jamming, he’s got his own four-piece outfit, formed early this year for a U.S. club tour that included a Detroit stop.

“If I want to play loud, growling music, I have to use my own band,” says Entwistle. “It’s a different mentality. That’s why I get a different feeling from my own band because it’s just the four of us.”

Onstage with the Who now, “it’s more regimented, and you can’t go off on a tangent — like you can with a smaller band — when you’ve got to take another 18 people with you.”

It’s been a busy life recently for Entwistle. An exhibition of his original artwork is accompanying the Who on its tour (a deal to show the stuff in Detroit fell through) and he’s eking out a light collection of Who memoirs, with plans to publish the first of three volumes next year.

On Nov. 19, Entwistle will release his sixth solo album. “Thunderfingers — The Best of John Entwistle” is a collection of his best solo songs, rerecorded with the help of guitarists Peter Frampton and Joe Walsh.

He hopes to give the world a second listen to more than two decades of material — music that never made it to many ears to begin with.

“If I had to do it again, I wouldn’t release it on the same label as the Who. I think a lot of it may have been held back because they didn’t want it to look like the Who was breaking up,” he says.

His albums have never been issued on CD in the United States, though Rhino Records tentatively plans to do just that.

But right now, the focus is on “Quadrophenia,” a musically versatile piece that Entwistle the Bass Player prefers to its rock opera predecessor, “Tommy.”

“There’s so much freedom in what I play on that. ‘Tommy,’ I guess, has got a lot more meaning, a lot more content, but we’ve played it quite a few times now,” he says, chuckling.

The new production “was hard to learn, but now that we’ve got a few shows under our belt, it’s starting to take on a different form anyway.”

The late Moon — possibly rock’s No. 1 all-time wild man — may not have dug these big, streamlined performances from the Who’s latest decade.

“I don’t know that he would have fit in into a large ensemble,” Entwistle says. “His playing wasn’t that kind of playing. It might not have come to this anyway if Keith was still alive. I’m really not sure what we’d be doing now. It probably would have gone in a completely different direction.

“I guess Keith would probably be in my band.”

Meanwhile, the man whose full, punching bass lines became a melodic jackhammer under the Who’s cacophony, keeps his mind on the tool that made his name.

“I’m playing better than I ever played before,” he says. “My fingers are even more nimble. It’s hard work, and I’m trying to keep ahead of myself. You have to really keep playing to get better.”

And he’ll keep playing ’til . . .

“’Til I drop, I guess!” he says with a laugh. “I mean, I’m working on three different careers now, and I don’t seem to have as many hours in the day as I should have.”

The Who “Quadrophenia” and other hits 8 tonight Palace of Auburn Hills $45, $70

Ticketmaster or 1-810-377-0100.

The Who’s Pete Townshend, Roger Daltrey and John Entwistle.