Maybe Irish music fans are remarkably open-minded, or maybe music genres have become so fractured that there's enough room for every possible kind of sound. But something is going on. A disproportionate amount of brilliant music coming out of this country happens to be instrumental. Whether by accident or design, a mash-up of genres – from heavy and math rock to electronic music, ambient post-rock, and sounds that simply can't be categorised – is spilling from venues and albums. And it's good. Really good.

On a Friday evening in Whelan's on Dublin's Wexford Street – a venue previously concerned with singer-songwriter heritage that has more recently had its roof blown off by a new generation of Irish bands – Adebisi Shank are about to launch their second album. During soundcheck, Vinny, the bassist, is showing off a tee-shirt his friend made featuring a drawing of him in the red cloth mask he wears on stage. It's his birthday, so he's looking forward to people buying him drinks later. Lar, Adebisi Shank's guitar player, waves over from the stage. He doesn't really do interviews, so instead, Mick, the drummer, makes his way upstairs to the dressing room to talk.

Mick also runs the Richter Collective with his mate Barry. It's an independent label at the heart of a new wave of quality music in Ireland, much of it instrumental. The label's roster reads like a who's who of 'right now'; Adebisi Shank, BATS, Not Squares, Jogging, Enemies, the more established Redneck Manifesto (of which the Choice Music Prize-winning Jape is a member) and more. If someone new starts working with the label, like another band, Logikparty, did this week, music fans immediately check them out. Nialler9, aka Niall Byrne, the country's best music blogger (who has the awards to prove it), says the Richter Collective "captured the imagination of a gig-going public who were ready to listen to rock music again".

Byrne has also had a hand in documenting and publicising emerging instrumental Irish music. "I think the amount of instrumental rock music in Ireland is just a part of a wider diversification of genres in this country," he says. Byrne premiered new Adebisi Shank tracks on his blog, a way of getting music out there before release that scoffs at major labels' ridiculous protection of unreleased music. "Their new album is one of the most imaginative albums I've heard not just in Ireland but worldwide and certainly not just in instrumental rock... They have a real fanbase, they're thrilling live. Their album launch was a result of two to three years of playing small venues, building up an audience, and it was no doubt helped by the stream of their album online in advance of the date."

Back in Whelan's, Mick is drinking a can of beer and reflecting on the reaction to their second record which has been earning massive plaudits. "I think it's mental. I think it's really surprising, it's lovely, it's really nice. It's bizarre." He tries to figure out why people like it, which is tough considering he finds it hard to describe the music his band makes beyond using the adjective "weird" a lot. "Maybe because the music we like is so out of context?" he wonders aloud. "I guess we make kind of weird music, but we like very straightforward stuff like Paul Simon and Peter Gabriel and Phil Collins."

Vinny comes in and grabs a can from the fridge. Mick tells him he's talking about what it's like playing their style of music in the UK. "They like vocals in the UK. It's pretty different," Vinny muses. "Probably at the start it worked against us because it was so completely different to what everyone else was doing in England. Now it seems to be working for us for some strange reason." He pauses. "People used to be like 'WTF', now they're like 'OMFG'. Or maybe 'LOL'." Mick shakes his head in mock despair and gives out to Vinny for "dropping internet phrases".

In a funny way, the joking adoption of internet language says more about the band than maybe Vinny meant. Adebisi Shank, from Wexford and Dublin, are a band who have embraced their online representation not just out of necessity, but because it's natural. (And so has the Richter Collective.) Their publicity, communication with music fans and distribution of their music happens in the sphere of Soundcloud and Twitter, not via press releases or 'listening parties'. Real life is for gigs.

The interesting thing about their new album is how diverse the sounds are. They've toured Japan, and you can hear that in the record. Perhaps the worldliness of the sounds reflects how any kind of music from any kind of place is available at a click right now. "Some of it has definitely come from getting out," Vinny says of those influences. "I hadn't been anywhere before being in this band, literally hadn't left the country. Oh, I went to Wales when I was six. Butlins! It's weird, a lot of people say all these sounds are from different countries, but some of it to me sounds real Irish for some reason."

Mick nods, and Vinny continues, "I don't know why that is, but I know I never really thought of myself as an Irish person until I went somewhere else. Suddenly you hear yourself talking [when you're abroad] and you're like, 'Oh my god, I'm a proper Paddy!' You feel like a big fucking shillelagh leprechaun man." Mick laughs and talks about picking up influences while seeing lots of bands when they are touring abroad. Vinny interjects, "Yeah, but Japanese bands don't sound Japanese." Mick agrees, "Yeah, they sound Irish actually!"

Despite their presumed internationalism, Adebisi Shank don't want to tour relentlessly. "I think there's a couple of ways to go as a careerist and the touring option just isn't an option for us," Mick says. "We love music, but it's not something I want to work at until I'm sick of it." "We don't want to turn it into a job," Vinny adds.

Enter another Irish band who do the complete opposite. And So I Watch You From Afar play so many gigs that when they were on their way to the South by Southwest festival in Texas last March, some people joked that they would probably play a gig on the plane because the flight was too long. They're another instrumental band, from Belfast and Coleraine, and are probably one of the best live acts in the world right now.

Tony, one of the foursome's two guitar players, chats on the phone about some upcoming gigs (Electric Picnic, the small matter of a 25-date US tour in October, followed by more UK dates in November.) He has a pretty conclusive answer for why Irish bands are doing so well at the moment. "We're all better! We're better than everyone else! I don't mean that in an egotistical manner, but the quality of bands coming out of this island is unreal."

He reels off the names of bands; "Adebisi, Enemies, Rednecks, Cast of Cheers... Although all our names are mixed in the same breath, the only similarities are that we don't have vocals. Comparing one with another is like comparing Slayer to Bananarama." He calls Irish bands "thoroughbred horses" in comparison to bands from other countries.

ASIWYFA play so hard that it's actually beginning to damage them. Johnny, the bass player, was recently in A&E because his shoulder is so badly injured. "He's getting on with it," says Tony with an audible shrug. Tony himself has had hernias from playing and from lifting amps. Last year, he checked himself out of hospital to play a gig when he woke up in casualty after being hit by a car. The complications suffered from stress-related problems due to such a hectic schedule also cause health problems.

"Every single part of it is worthwhile," he says. "We're doing what we love and what we've dreamed of, so we're not gonna let a few shitty health scares get in the way." For ASIWYFA, touring has become a necessity. "If we don't keep busy, you know, bad things happen. They say the devil makes work for idle hands, but it's more like the devil possesses us and makes us do terrible things. It's better to have us together and to have a set goal. If we're all separated and left to our own devices, I couldn't even go into what happens."

That Friday night, Adebisi Shank tore Whelan's apart. The place was packed, the sound was loud, the crowd surfing was boisterous, the sweat was dripping.

"It's [instrumental music] kind of acceptable in Ireland," Mick says, before they take to the stage. "People don't ask you, 'Where's the singer?' Apart from your mammy! I don't know what that is. The only time I realised it is when we went to England and people are like, 'You'd sound great with a vocalist.' It was never really an issue back home."

It can hardly be an issue when it's this good.

Adebisi Shank's second album 'This is the second album of a band called Adebisi Shank' is out now on Richter Collective. ASIWYFA play Electric Picnic on 3 September. Niall Byrne's blog is www.nialler9.com. For more, see www.richtercollective.com