"New York...California...on the road," he says, his speaking voice as candied and languorous as it is on record. "I try to live light." It's not by choice, he emphasises, but rather necessity.
Forward motion and restlessness are themes that pepper the 37-year-old's canon, which swelled to seven albums with the release of double LP Big Wheel And Others last October. The rumbling, rolling title track opens with: "I dig the taste of diesel and the sound of big rigs/ Rubber, metal, oil and stone/ Scoring at truck stops, lot lizards and driving far alone."
McCombs's is neither folk nor country, rock nor soul, yet touching on all four, as nomadic as its creator.
There's no money in touring at his level, he tells me. He can't put his band on a wage - "There's nothing to pay them with" - and he can't afford roadies. So why tour? "It's a reward, it's what it's is all about," he says. "We get to travel and talk to people and learn about what's up in these different places, instead of reading it in a newspaper - which is valuable - but to hear what people are saying about politics or whatever, it's essential.
"What it comes down to is feeding off that moment. It takes a long time to create the space where that microsecond of creation can exist. Because life is just a crazy science experiment, like a mad doctor's laboratory, and it could go one of a million different ways."
With nothing but musical satisfaction to offer his band, how does he keep a steady - and happy - line-up? "There's a loose policy to the band, how it's organised," he says. "It's like a tag team. I understand people come and people go - that's natural. Everything should be fluid and natural, and imitate the natural world. So if you've got to go you've got to go. But I'll find a replacement."
The singer is speaking from New Jersey, where he is spending time having just completed a North American tour before heading to Europe next week. McCombs's show in Scotland on Thursday will be his third time in Glasgow. Asked for his fondest memories of the country, the road takes centre stage once more.
"It's always so wonderful driving into Scotland," he says. "It's such an emotional experience just to watch the terrain turn...Scottish," he chuckles.
McCombs's oh-so Californian evenness vanishes briefly at the suggestion he should visit the Highlands. "Oh, I would love to," he says animatedly. "One of these days."
Until then there is the endless road and recording with which to keep busy. Having delivered seven albums in 10 years, besides his debut mini-LP Not The Way in 2003, McCombs is among the most industrious artists around. How does he view the evolution of his music?
"I don't really think about it, y'know? I don't like mirrors. I have this thing with some friends of mine, where if a question is too personal we say: 'That's a mirror.' When you look in a mirror you can do your make-up or fix your hair but it doesn't actually show you what you look like.
"It's a reverse image and it's a distortion. It's not even three dimensional. It's a two-dimensional reverse image of yourself. I feel the same way about trying to assess my feelings on myself. It's not up to me to know."
While his records are dotted with musical and technical imperfections (his second album, PREfection, concludes with 10-plus minutes of a car alarm going off), it's possible McCombs's profile is most hampered by what can be interpreted as prickliness, but which is in all likelihood little more than a distaste for the rules of the game. Here is a songwriter with all the chops of, say, the late Elliott Smith, Josh T Pearson or Jimmy Webb, but little of the kudos. Is he a square peg in a round hole? "I don't know if I'm a square," he says, sniggering. "Maybe a rhombus or a triangle. A giant triangle trying to fit into a tiny hole."
How, then, does McCombs explain his failure to prosper, financially if not creatively? "There are so many factors to making music. There's music, that's number one. That exists beyond any business model, before all the chatter. It's a very tranquil dimension. Then you sprinkle in the physical reality of trying to perform that music, and the gas it takes to be able to do that.
"Then there start to be corrupting agents, and it takes effort to maintain music as just music. You want to keep it music, and everyone wants to turn it into some kind of dialogue. Well no, I don't want it to be a dialogue. No-one wants it to be a dialogue except you."
At this juncture McCombs is at his liveliest. Whether by "you" he means music writers or not is unclear.
"It's not a dialogue. It's not a concept. It's not a genre. There's no reason - it's just music. Can't we just have our music be music? Why does everything in the world have to be commerce? I don't get it."
His point made, McCombs collects himself and continues: "I actually like this business. It's ****ed-up and stupid and wack, and everyone's wrong, but I kind of like it. It's like prison - it's evil and awful and scary but it's real, and in some ways it's better than not being in prison."
I ask what he'll do when he hangs up the phone. "I'm just gonna walk around in the snow a bit. It's a winter wonderland out here." Another echo of restlessness. For Cass McCombs, drifting beats standing still every time.
Cass McCombs playes CCA, Glasgow, on January 9 (doors 8pm). For tickets, priced £8.50 plus £1 booking fee, visit www.cca- glasgow.com or call 0141 352 4900.