Best speakers for classic rock

Cerwin Vega if its all about the bass, bout the bass, not the treble (or midrange for that matter).

Look for used OHMs otherwise.  Model L, C2, Walsh, others   Those can even be upgraded at teh factory to modern specs if desired.

Atmasphere hit the nail on the head, which has been said before. BTW...…...Paul W. Klipsch did not listen to rock. When someone asks me what speaker is good for rock, I make an assumption that they are a headbanger ( listens loud ). I appreciate a system that can handle peaks, cleanly, at and above 100 db, which I feel few systems can do, which is a reason I like horns.

Look for brands that taught low distortion at high volumes . I think classic rock means high db's . From what I have owned I would list ,Axiom , Bryston (upgraded Axioms) , JBL , Cerwin Vega , Revel . There has to be dozens more brands that will work 

Also , Those speakers I listed played all genres of music equally well . The key was they played loud without distortion .

The JBL L100 classics are excellent.  On rock.  On non-rock.  On music.  I have them.  In a third system.