I am not familiar with the Big Ears fest. But I live about 80 miles east of Knoxville and am familiar with the local area musical vibe. You may also like the Rhythm & Roots Fest in Bristol TN/VA. It generally happens in early Sept.
FWIW, Bristol has been proclaimed as the home of country music. This is because Mother Maybelle Carter & the Carter family were first recorded there and got radio play also, somewhere around 1927 (?) As a consequence this area has become very involved in Bluegrass, Country and Roots music in general