It's been two decades since Metallica introduced their fans to "S&M."

For those with their minds in the gutter, that's an abbreviation of "Symphony and Metallica," a thrilling collaboration with the San Francisco Symphony that reimagined many of the band's classic songs such as "Master of Puppets," "One" and "For Whom the Bell Tolls" with orchestral arrangements.

The first "S&M" concerts were staged and recorded in 1999, spawning a hit live album that sold more than 8 million copies worldwide. To commemorate that album's 20th anniversary, Metallica reunited with the San Francisco Symphony for a pair of sold-out shows known as "S&M2," which opened the city's Chase Center arena last month.

Fortunately for fans who missed out on the epic event, "S&M2" was filmed and edited into a two-hour concert movie, which screens in theaters nationwide on Wednesday, with repeat engagements scheduled on Oct. 13 and 14 (visit metallica.film for full listings and tickets).

USA TODAY caught up with drummer Lars Ulrich, 55, to chat about revisiting "S&M" and the postponement of Metallica's overseas tour after the announcement that vocalist James Hetfield reentered a treatment program for addiction.

Question: Looking back to when you announced the first "S&M" live album and concerts in 1999, what did people make of it at the time? Did they question how Metallica and a symphony would fit together?

Answer: Over 35-plus years, you grow immune to the different things people throw at you. But generally, the fans have been appreciative of our sense of curiosity and openness to different ways of doing Metallica's music. So the response has been mostly positive. Certainly, when it comes to hard rock, there's always somebody that will throw their two cents in. Everybody has an opinion nowadays, maybe more so than 20 years ago. But Metallica has always moved forward and not paid too much attention to what people expected of us.

Q: Were there any songs you were most excited to revisit during last month's shows?

A: I was really excited about the new possibilities. We knew early on that rather than just repeat what we did 20 years ago – but with more gray hairs and 20 additional pounds – that there was an opportunity to once again put the creative hat on. So we looked at all the original material that we've released since '99 ... and picked six or eight new songs that could give the project a sense of (currentness).

Q: What new moments do you feel worked best?

A: A lot of the new songs from the "Hardwired ... to Self-Destruct" album that came out a couple years ago worked really well. (Director Michael Tilson Thomas) suggested this piece by Alexander Mosolov called "Iron Foundry" and to put our music on top of that. We were also curious about what it'd be like if there was a piece where the orchestra played all the Metallica parts and James did the vocal over it, which was the song "The Unforgiven III" from the "Death Magnetic" album. So those moments were really exciting because they were fresh and unexplored and creatively felt edgy. That was a lot of fun.

Q: Have you yourself ever played strings?

A: I would be lying if I said that I'd never held a string instrument in my hands. I've certainly dabbled and sort of worked my way around a violin, but that's probably best left to the trained professionals. I'm quite happy where I am, holding it down in the back. (Laughs.)

Q: Do any of your sons play instruments?

A: They've all played many different things: guitar, bass, a couple of woodwind instruments. All three play piano, and one guy is an incredible drummer.

Q: How do they feel about what you do? Do they think Metallica is cool?

A: I don't think any of them think Metallica is "uncool." They appreciate what I do for a living and where my passion is, and it's a pretty musical household: There are guitars lying around in all the rooms, we've got a couple drum kits and a piano downstairs. There are always lots of conversations about music, and living in Northern California, you spend quite a bit of time in your car (listening to) music. From a very early age, I would play them Guns N' Roses, Black Sabbath, Rage Against the Machine, System of a Down. So they've grown up on a lot of rock, but one guy's very interested in jazz fusion and some progressive things, too.

Q: Metallica's self-titled album is celebrating its 30th anniversary in 2021. Given what a huge album that was and how many hits it spawned ("Enter Sandman" among them), do you have any big plans to blow that out?

A: When you've been around as long as we have, there's an anniversary almost everywhere you look. I believe next year is also Metallica's 40th anniversary since we started in 1981. So there's lots of anniversaries all the time, and we do respect those, but we do like to spend most of our creative energy looking forward to new projects. So there's no specific (plans) that we've talked about, although I'm sure as we get closer to some of these dates, we'll figure out what we can get our hands into. There's no shortage of different spins on things from the past, and also different pathways into the future. The thing we mostly celebrate is just being around and still playing.

Q: You guys recently announced that you're postponing your fall tour of Australia and New Zealand as James reenters rehab. How is he doing now, to your knowledge?

A: He's doing what he needs to; he's in the process of healing himself. I feel bad for everybody down in Australia and New Zealand, but we're excited to get back to full force and come back stronger and healthier than ever. Along the way, there's obviously an occasional bump in the road. But it's been an incredible ride, and we're looking forward to getting back down there, hopefully next year.

Q: James has been vocal about his struggles with addiction and sobriety through the years. Were you surprised when he told you about his decision to return, or how did you react?

A: I don't have anything more to add – we put out a statement a week ago. I think the biggest surprise is just how positive the feedback has been from our fans and friends and peers alike. It's very heartwarming, and it's just blown our minds how much love and appreciation and support we've gotten in the last week since we had to postpone this. It's an incredible thing.