"I don't regret it a bit, because at17 came to a point where we didn't really know what to do next, musically," she says. "I was writing my own stuff and didn't want to compromise what at17 was doing because we'd this electronic folk way of expressing ourselves."
Loo and Eman Lam Yee-man formed the Canto-folk duo in 2002 after meeting at a singing competition several years before. They proved a refreshing change in the usually cookie-cutter Canto-pop industry. Straddling the line between indie music and Canto-pop, they gained fans with their upbeat tunes about typical teenage problems.
The group disbanded in 2010 and Loo then began her solo career. She has since released two albums and, earlier this year, headlined her own concert at Queen Elizabeth Stadium.
Loo admits that she was scared at the beginning of her solo venture. She says: "I had no idea what I wanted to do besides writing songs. That was the only thing I wanted to do. I had to force myself to go to Taiwan. I sang on the street, I performed until I knew what values I had and wanted to present to people."
She spent about a year performing at universities and music festivals in Taiwan. And it was at this time that she started to wonder why there were no similar music festivals in Hong Kong. So when she was offered the chance to play at the forthcoming Clockenflap Music Festival, she was delighted.
"I saw a couple of pictures from last year's event and my first impression was of the beautiful sunset over West Kowloon," she says. "I think it's really rare to have such a large music festival in Hong Kong, with the whole amazing scenario and atmosphere."
Loo believes that, while it's great that the city is hosting more music festivals, such as Clockenflap and Lion Rock Music Festival (at which she performed this month), there also has to be real "fans".
"I think Hong Kong is still at an early stage," she says. "I don't want to use the word 'educate', but we need music lovers that will actually appreciate bands even if they've no idea where they come from ... I don't want people just to come to see me or Franz Ferdinand.
"You want people to appreciate music that maybe they don't normally listen to. That's the whole point of going to a music festival - you can listen to new stuff. You can discover new bands."
As well as performing, Loo is also looking forward to watching some of the different acts herself. Perhaps she will even be watching with Lam, her former musical partner.
"I think we're better friends now than before because we don't have business issues anymore," Loo says.
"We don't talk about our music that much, but we do talk about each other's lives and have more time to be real friends, instead of simply being band members."
Clockenflap takes place from November 29 to December 1, at West Kowloon Cultural District