Two years ago, Donald Fagen, Michael McDonald and Boz Scaggs formed a like-minded touring trio, dubbing themselves The Dukes of September.

It was a bit of a throwback to the New York Rock and Soul Revue the guys performed with others in the early '90s, and a solid success, drawing Steely Dan and Doobie Brothers fans, also the demographic that grew up appreciating the solo work of all three.

What was apparent from the start of this partnership, though, was that self-indulgence was OK, because every night, the Dukes would dig deep into their own well of favorite covers, pulling out tunes such as Don Covay's "Sookie Sookie" and Lee Michaels' "Heighty Hi."

Now, they're back for a second round of touring and coming to the Verizon Wireless Amphitheatre in Alpharetta on Friday.

In a recent conference call, McDonald and Scaggs (Fagen was expected, but never arrived) discussed their process for choosing songs, what they might do differently this time and whether or not a Dukes visit to the studio is a possibility.

Q: What did you learn from last time out together that you wanted to do differently this go-around?

A: [Scaggs] I don't know that we really learned a whole lot. I think most everything we were doing felt good. But we've got a new set list, new arrangements. Mike and I had a chance to get to know the band better, since Donald is used to working with them.

[McDonald] If we learned anything it's that we can push a little more with some of the material. In the first round, we wondered how obscure we could get and we did covers from The Grateful Dead, The Beach Boys, The Band. Our aim is to always pick songs that when people hear them they go, 'Oh, man, I haven't heard that in years.'

Q: What's your process for choosing a set list?

A: [McDonald] We communicate by email in the beginning and throw songs into the hat and try to figure out what might work, knowing it will get boiled down to a two-hour show. We leave it up to Donald a bit to decipher, since he's the musical director.

[Scaggs] We try to balance it out. We do our own songs, but I'm always looking for something I can sing with Michael or all three of us can sing on. We share a common thread of music. R&B is where we all land.

Q: What does each of you bring to the stage?

A: [Scaggs] I could go on about Mike or Donald. Donald has great arrangement skills and a unique voice and a particular slant on life, on music. Michael's got a unique voice. I'm the token Okie, so I don't know what I'm doing in the mix!

[McDonald] Boz brings a traditional blues and deeper R&B knowledge with his guitar playing and Donald has the arrangement and jazz background that brings an interesting flavor to the arrangements.

Q: What are some of the challenges you face that is different than touring with your own band(s)?

A: [Scaggs] The setting is just different and unique. This band has a style. And the variety of the material means that I'm stepping into roles that I would never step into in any other musical context. I'm singing lead songs on songs, like the last time we did 'Love Train.' We did a medley of Band songs... So we're getting to use our voices and our chops in ways that would never present themselves.

[McDonald] I think we're out of our comfort zones in ways... And it's kind of terrifying at first, but it's a lot of fun in the end. It does a lot for, I think, the three of our spirits just as musicians and getting a chance to do this. It's really a kind of rejuvenating experience, I think.

Q: Any thoughts to going into the studio to record together?

[Scaggs] You know, it's never been discussed. I think it's been an obvious question. It's been an obvious choice. My personal feeling — I don't know — I would imagine Mike and Donald share to some degree that once you start recording...once the cameras go on, the red light goes on, it complicates things. It's not doing it for the original reason, at least for me. I'm of a generation that we do what we do. You want to do it from the heart. You don't want to feel self-conscious about it...The purpose of this exercise was not to record, which is not to say that after you've done 20 or 30 cities that you're hitting on some stuff that is very much its own. And it could very well happen.

[McDonald] Yes, I agree with that. I think that at the very heart of this thing, it's a live show. That's just kind of what it wants to be and maybe nothing more.

Concert preview

The Dukes of September with Donald Fagen, Michael McDonald and Boz Scaggs

8 p.m. July 20. $25-$89. Verizon Wireless Amphitheatre at Encore Park, 2200 Encore Parkway, Alpharetta. 1-800-745-3000, www.ticketmaster.com.