Classic rock as in the 70s? I've never come across one that is totally dedicated to that genre (usually they are mixed in with classic 80s metal). I don't think there is much of a niche for classic rock on independent websites. The 70s wasn't much of an "underground" era...unless you're talking punk. All the really good hard rock/metal bands had record deals (and are still played on classic rock radio) because the genre was just being born...they were the pioneers and they are still household names if there is an elder music fan sleeping in one of the bedrooms.
Have you been surfing progarchives.com? If not, that's where you should be looking, Soundmaster.
NP: Pantommind - Shade of Fate