The phrase "a mainstream level of" is correct and usable in written English.
It can be used to describe something that is typical or widely accepted within a particular context or field.
Example: "The product was designed to meet a mainstream level of quality that consumers expect."
Alternatives: "a standard level of" or "a common level of".
Special education schools form a level below the lowest mainstream level of the Dutch secondary education system.
Pre-vocational schools form the lowest mainstream level of the Dutch secondary education system.
His moody anthem "Faded" was a most vital track of 2014, bringing mainstream levels of attention to the fast-emerging stateside deep house trend.
I guess my message would be this: It is simply ridiculous, in 2012, for there to be as much marginalization of bisexuality as there continues to be, both at a mainstream community level and also at the level of scientific inquiry.
But for parties outside the mainstream, the level of work you need to put in is equivalent to a full-time job," he says.
This year Mr. Fairey has earned a new level of mainstream attention thanks to the much distributed and copied Obama poster, highly visible at the Democratic National Convention in Denver and, as a T-shirt or accessory, on a liberal body near you.
Twitter actually began working with HackerOne three months ago according to its bug timeline, but it seems the Apple celebrity photo hack has catapulted cybersecurity to a new level of mainstream interest, and Twitter wanted to show that it takes keeping its users safe quite seriously.
Birtherism received a strange level of mainstream legitimacy via ambassadors like Donald Trump, Sarah Palin, Rush Limbaugh and, yes, House Speaker John Boehner.
As writers at Wired and io9 have noted, the issue marks a new level of mainstream interest in science fiction, giving a whole cadre of New-Yorker-obsessed "serious readers" license to take genre fiction, well, seriously.
It was good to see songs like Boobie Miles and R.E.M. performed, but the fact that Big K.R.I.T. pulled from his mix tape library and not his mainstream, created a certain level of disconnectedness to the effort.
