It seems hard to imagine, somehow, but more than a decade has passed (almost 14 years to be exact) since the debut album of Solas, whose members at the time included guitarist John Doyle and lead singer Karan Casey. To many ears, Solas was a revelation, creating an Irish-American sound built on tradition but clearly pointed toward contemporary styles and influences. Doyle's accompaniment - sometimes relentless, other times lyrical - provided inspiration for more than a few guitar players, while Casey attracted attention in her own right, her vocals high and clear, but demonstrating an unmistakable strength and resolve. The fact that as a college student she had been a jazz singer (and did a mean impersonation of Ella Fitzgerald) and studied classical music made her all the more intriguing.

Casey and Doyle left Solas within a year of each other during 1999-2000 but certainly did not become strangers: Doyle appeared on Casey's second solo CD, "When the Winds Begin to Sing" and toured as part of her band at one point, and Casey returned the favor on Doyle's first solo CD "Evening Comes Early." The two also took part in the Solas 10th anniversary performance in 2006, which was released on CD and DVD.

Now, Doyle and Casey have joined forces to tour as a duo with a just-released CD, "The Exiles Return," to their credit. This month will see them play three dates in Massachusetts: Feb. 7 at Club Passim in Harvard Square; Feb. 10 at Northampton's Iron Horse; and Feb. 25 at the Katherine Cornell Theater in Vineyard Haven.

Late last month, Casey - having just returned to Belfast after performing with Doyle at Celtic Connections in Edinburgh — spoke by phone with the BIR and talked about her new/old collaboration, among other things.

BIR: You're no stranger to the Boston area, obviously, what with performing in "Christmas Celtic Sojourn" and at Irish Connections. What kind of associations does the place hold for you?

KC: I did lots of gigs in The Burren , and in fact that's where I had my first night out with my husband [Niall Vallely], because we both happened to be playing there. Johnny D's was where I did one of my first gigs with Solas. And I was involved in a performance at Symphony Hall as well. There's just an awful lot going on in Boston, and I love it. It's like doing a gig at home: People know what's going on, they know what to listen for, and they get the jokes.

BIR: So how did this collaboration with John come about?

KC: We would see each other every so often, and we'd say "Yes, we'll definitely do something together." We never did - and now we have! It was just a case of setting aside some time and being able to focus. I had finished my last CD ["Ships in the Forest"] in 2008, and then the two of us went to Nashville and started recording. It's just great to be playing with John. We have very much the same ideas about songs, what we like and how we want to do them. I feel like I'm on some sort of cloud when we're performing. He's just so good - if I miss a beat, he's right there! (Laughs.)

BIR: Did you approach "Exiles Return" with a certain point of view, that there was a statement of some kind you wanted to make, musical or otherwise?

KC: We wanted it to be all about the songs, and about really exploring what's going on in them. We felt strongly that we had to get into the depths of the songs, and that's why on most tracks it's just John and me, although we were really pleased to have Michael McGoldrick and Dirk Powell with us at times as well.

Ten years or so ago, it was different for me. When you're still kind of new to music, and you go into the recording studio, you get excited: "Oh, I want to have this and that, and let's bring in a massive band here." I'm not trying to demean that, but it is a phase in many ways. I feel more adept and confident in my singing, and so for me there's not as much need for lots of other things to be going on behind me.

This album is simple — not simplistic, but simple. You have to be confident about your singing, and more to the point you have to be confident that the songs you're singing will draw people into them. That's what we were looking to do.

BIR: What about the songs themselves? Was there a pattern or a theme you had in mind?

KC:I suppose there are a lot of lonely songs on the CD. I think I wondered at some point, "Will they all be songs of abandonment?" But you know, that's such a massive part of the Irish culture: abandonment, loss, not having what you need, emigration, war. The important thing for us, though, was to have songs with emotional depth. It's in our nature — we just don't go for the uptempo drinking songs.

"Exiles Return," which John wrote, is a perfect example of that. John's been in the US now for almost longer than he's spent in Ireland, and he talks about being neither Irish nor American at this point. So the song is about all those immigrants who know the sadness of leaving home but also the joy of finding a new life.

I actually found it hard to sing "Exiles Return" and I don't know why, but at the beginning I couldn't get through it without crying. At least when I sang it in Glasgow the other day I didn't cry until afterwards.

"Sailing Off to Yankeeland," which is also about immigration, was another song on the CD that felt special for me, especially since I associate it with the singing of Frank Harte, who was a hero to me. I liked that it offers a hint of the American side of the story, that there was this sense of moving forward. And "Bay of Biscay" is such a very tender song, and it draws you in.

BIR: You mentioned that you began this CD not long after "Ships in the Forest" came out. There was a very quiet, subdued tone to that album, and you had said something to the effect that the songs reflected your concern whether Ireland - having settled into a post-colonial era with some reasonable prosperity and self-confidence - would be able to confront "the difficult events of our past and present." Where do you see this CD in relation to "Ships in the Forest"?

KC:The feeling I tried to convey in "Ships In the Forest" was that there is so much grief in Ireland's past, and when and how do we get out of it? When do we turn it around? I think we certainly tried to in the Celtic Tiger era, but I'm not sure how successful we really were. I feel there's more of a sense of release in this CD, and especially because it's truly a joint effort between John and myself; we're in this together.

BIR: Is working with John a different experience now than it used to be?

KC:Well, we're both mellower, a bit kinder, not all welled-up; certainly more easy-going. And we've got families: John has a little girl, and my daughters are 10 and 3 ½. So we're probably a lot more efficient and organized than we were. All those things help a lot on the road! Also, we didn't want to just fall into the old roles we had in Solas. We wanted this to be a duet, where we really share in the work. That's been very important from the start.

BIR: You've built up a body of work by now, whether with Solas or on your own, and achieved a stature in Irish music—

KC:I've become part of the establishment, yes. (Laughs.)

BIR: Do you get a sense that there are female singers coming of age now who've looked to you as a model, an inspiration?

KC: I do hear that, especially in America, it seems, and it's a very nice feeling. In the folk world, we eke out a living, and we don't have the fame and fortune like in the "mainstream" music. So to hear that you've influenced someone, or had some kind of impact on them in their enjoyment of music, it really does mean a lot.

BIR: Is there anything that strikes you about singers in Irish music today?

KC: I have to say I'm a little concerned. I'm not sure there's as much of a platform for singers as there used to be. I find it troubling that there seems to be a growing separation of the song and instrumental traditions, where in the past people like Frank Harte, for example, really believed in keeping all the music, the songs and the tunes, together. Now musicians will play the tunes, and then when a singer gets up to sing it's like a "break time" for everyone. So it makes me wonder: If nobody knows you, where do you get a chance to sing? How do you get the first foot on the ladder? I suppose there's an ebb and flow to these things, so maybe it'll get better.

BIR: Any other projects in the offing?

KC: I'm working with Aoife O'Donovan on a CD, with Seamus Egan [from Solas] producing. It's not so much a traditional album, though. We're kind of feeling our way through it, but hopefully it'll be out at the end of the year. I suppose that's the thing about getting older: I'm only doing what I really, really want to do now. You know it has to be worthwhile for me to leave the girls. I'm not going to go out on a tour just for a lark. I'm not a road hog any more.

Opening for Karan Casey and John Doyle's Club Passim show on Feb. 7 will be local duo Liz Simmons and Hannah Sanders, who sing songs culled from the British Isles and North American folk traditions as well as their own compositions. Simmons, a member of the bands Annalivia and Long Time Courting, has performed with Casey as well as Aoife Clancy, John Whelan, North Cregg, and The Sevens. Sanders, like Simmons, grew up in a musical household, and traveled and sang across the UK and Europe with her family band The Dunns. The two have appeared as part of the Boston Celtic Music Fest "Celtic Music Monday" series and at Studio 99 in Nashua, NH, among other venues.