Nearly half of the UK's classical musicians don't earn enough to live on, says the Musicians' Union (MU).
Although rank-and-file members of the BBC Philharmonic or City of Birmingham Symphony Orchestra are paid about £30,000 a year, wages have stagnated as funding cuts take hold.
Young musicians are particularly affected, with two-fifths of newcomers taking unpaid work in the last year.
Forty-four per cent of players told the MU they struggled to make ends meet.
And two-thirds of veteran musicians - who'd been playing for more than 30 years - said they'd considered alternative careers.
"Wages are increasingly depressed," said Michael Kidd, who plays French horn with the City of Birmingham Symphony Orchestra.
"If it continues in that direction, it's not going to remain a viable career option."
The 29-year-old, who played at the wedding of the Duke and Duchess of Cambridge, receiving a piece of wedding cake from Prince Charles as a thank you gift, told the BBC that many musicians were also saddled with debt.
"A lot of the string players are basically having to take out a mortgage to buy an instrument on top of a not very good salary," he said.
Flautist Jemma Freestone says she, like many other players, supplements her salary by taking other music-related jobs.
"It's becoming increasingly obvious that playing your instrument is a small part of what is needed to survive in this industry," she told the BBC.
"For me, that's a brilliant thing. I love teaching and I love doing workshops but for some other people that can be very difficult.
"All you learn in music college is how to play your instrument. You don't learn these auxiliary skills that, in reality, you need to survive."
Ms Freestone plays with the Southbank Sinfonia and the National Theatre, aside from her teaching and outreach work. But she notes that in other European countries, orchestral musicians "the salary is far higher".
"Perhaps it's not valued enough as a profession," she said.
"We study for five, six, seven years. It's very competitive, and it's very difficult to get a job as an orchestral musician. And when you get there, you like to think that that's enough.
"I don't think anybody enters music for the money," she added, "but you do have to earn a living".
Orchestras 'could close'
Mr Kidd said many of his orchestral colleagues lived under the constant threat of unemployment.
"It's reached a point where [we] are having to rely increasingly on generous concert-goers - not just ticket buyers, but the few that are prepared to pay a little bit extra to keep supporting the orchestras," he said.
"Obviously we're all very passionate about what we do. But if we're entirely reliant on the goodwill of our audience, you inevitably have the fear of 'Will this survive?'.
"It could all go belly-up."
The Musicians' Union surveyed 285 musicians in seven orchestras across the UK to reach its findings.
To highlight their predicament, the organisation is launching a campaign, Musician Behind the Moment, to remind people of how valuable orchestras can be - in the hope fans will put pressure on the Arts Council and local councils to increase funding.
"Even if you're not a classic music fan, you probably interact with orchestras more than you realise," said Naomi Pohl, the MU's assistant general secretary.
"So if you're watching your favourite TV programme or film, or playing your favourite video game - orchestral musicians are on those soundtracks.
"Also our members do a lot of work in dementia homes and hospitals now, as well as in education settings, like teaching a child a musical instrument for the first time.
"We know there's not an unlimited pot of money but we're trying to make the point that orchestras are really valuable resources in communities. We want to see a bit of an increased priority for orchestras."
"The worst case scenario is we'll see a lot of orchestras closing," she added. "It would be disastrous."