To do so meant leaving a Chihuahua alone in a house she has been looking after and heading a few miles into Manhattan to catch up with some old friends.
These familiar faces included James Milne, whose group, Lawrence Arabia, was supporting Crowded House.
Liam Finn was there too, his presence thus bringing together three-fifths of the tongue-in-cheek "supergroup" Barb, whose other members are Connan Hosford (of the band Connan Mockasin) and former Mockasin drummer Seamus Ebbs.
The quintet are good friends. Over the past several years they have shared adventures musical or otherwise in various parts of the globe, including London, where the seeds were sown for their latest project.
Having moved from Melbourne to London in 2005, initially sharing an East London flat with Milne, Finn offered Barnes his room to sub-let while he visited New Zealand.
On Finn's return, Barnes was singing with Milne's band, Lawrence Arabia. Finn ended up pinching her for his own projects, the pair then touring constantly on the back of Finn's 2007 solo debut album I'll Be Lightning and last year's EP, Champagne in Seashells.
Yet despite all their various projects, the five musicians co-ordinated their schedules and shared a month in Auckland in spring last year.
The occasional foray to Piha notwithstanding, they largely spent the time recording at Roundhead Studios (and why not, given Liam's father owns the place).
"We had a month and we would just go in each morning and try to write something," Barnes explains over the phone.
"Everyone would play and take ideas and run with them.
"There might have been a couple of old ideas that people brought to the table but it was pretty much all spur-of-the-moment collaborations.
"Everyone's music is so different. I love all their songs.
"I think everyone has a love of playing one another's songs, which obviously leads to the desire to write together. It is a party record. It is not serious in any way, really. It was purely for indulgence."
The result is a self-titled album that bursts with energy, humour and occasional electronic noodling.
Although not quite shambolic, the songs are loose and relaxed, conveying a sense of familiarity in the musical relationships and, typically in the case of Finn, a mix of strong melody and psychedelic whimsy.
"It is amazing how the atmosphere can change in the studio at different times of the day," Barnes laughs.
"We went through lots of phases."
Evidence of one such "phase" can be found on the band's web blog, on which the four male members of Barb can be seen gyrating to the strains of Not A Bird.
Significantly, Barnes appears a late and reluctant participant.
She says she's not much of a dancer. She much prefers singing.
Having left her Sydney high school and gone on to sing backing vocals with older sister Mahalia in her father's touring band, Barnes is no stranger to the stage, yet she has been enjoying some time away from it of late.
Based in New York for the past two and a-half months, she has had a range of jobs, from waitressing to selling theatre tickets - "not the wisest career move . . ."
She has just completed an album with a fellow Australian singer, the duo going by the name Evil J and Saint Cecilia.
"We've just finished mixing it, actually. We recorded it when we were both in Sydney at the start of the year before I came over here.
"My dad recently acquired a tape machine so we went in and tried to make a record in a short period of time. It's done but I don't know when and where I'm going to release it."
Barnes still finds time to perform with her dad.
Jimmy was in Los Angeles earlier this year to record an album, on which she contributes backing vocals.
"On his last record, Out Of The Blue, we wrote a song together. It's called Everything Is Changing."
Like her father, Barnes finds herself dipping in and out of musical genres.
"I have broad tastes. It's like choosing a favourite food - how can you decide?"Which brings us back to Barb.
It's a band that is hard to define, impossible to pigeonhole.
"Because it isn't a solo project, it has been liberating.
"It meant everyone could be unguarded and free."
• For the record
Barb's self-titled album will be released on August 6.
