If one is the loneliest number and three’s a crowd, then two is sublime, at least in musical terms. Just ask John and Paul, Mick and Keith, or recent Rock & Roll Hall of Fame inductees Hall & Oates. Duos have been a part of rock’s history from the beginning, with the Everly Brothers and Simon & Garfunkel finding massive success in the ’50s and ’60s to recent chart-topping albums from the Black Keys and Daft Punk.

Indie duo Milk Carton Kids are also well aware of the power of two. Neither Kenneth Pattengale nor Joey Ryan had had much luck in the Los Angeles folk scene as solo performers, but after pairing up, their fortunes changed. The dapper duo gave away nearly 300,000 copies of their first two albums for free on their website, and in 2013 issued The Ash & Clay for acclaimed L.A. label Anti-. We caught up with Ryan to dive deeper into two-man bands, and to take his pulse on some duos that seemed to be less-obvious influences on the band than Simon & Garfunkel or Gillian Welch and David Rawlings.

SW:

What are the pros and cons of being a duo?

Ryan: It’s very much like a marriage. It’s equal to the difference between being a single person and a married person, with all of the benefits and drawbacks that come from that. Compared to being a solo artist, personally I think it’s an enriching addition to one’s musical life. As compared to being in a larger band, I don’t have any reference.

How do you break a tie in a two-person group?

Somebody’s got to give in. We have a government shutdown every now and again. We’ve given ourselves each veto power over every decision, and you have to be responsible with veto power—you can’t just filibuster everything.

Do you ever worry that your partnership will end up like Wham!: Kenneth will become George Michael and you’ll end up Andrew Ridgeley?

I have thought about the ominous history of a lot of duos. There’s not that many of them that end up on speaking terms after very long. The Everlys—and they were brothers—I think they had to get separate tour buses at the end. I’m pretty sure Paul [Simon] and Art [Garfunkel] are not buddies. If it’s anything like the divorce rate, you’ve got about a 50-50 shot.

How do you figure out who will sing melody and who will tackle harmony?

Usually it’s whoever’s voice sounds better singing each part. Sometimes it’s obscured even to us which is the melody and which is the harmony. We try and treat it less like a harmony line and more like a countermelody. Usually the vocals are blended in such a way that one is not a lot louder than the other, and they’re both composed to be able to survive on their own.

Can we do a rapid-fire duo round? How do you feel about Tenacious D?

I haven’t listened to them in a long time, but I used to watch their videos. Those guys are geniuses.

Black Keys?

I’ve never gotten familiar with their music.

Eurythmics?

I didn’t know that was a duo. I liked when their songs came on the radio.

Rodrigo y Gabriela?

I’m very impressed any time I see their performances.

Outkast?

I dig Outkast.

Hall & Oates?

Take it or leave it. They’re great songwriters, sure.

Daft Punk?

Their song from last year is atrocious and everybody lost their mind over it. It’s insensitive to say that because I know they are human beings, but I think they’re big enough that we can be honest about what we think.

music@seattleweekly.com

MILK CARTON KIDS With Tom Brosseau. The Neptune, 1303 N.E. 45th St., 682-1414, stgpresents.org/neptune. $20. 8 p.m. Wed., June 11.