I find it strange that loads of people are suggesting a Crunchbox when the OP states he wants something for Classic rock.
The Crunch box is a fine pedal, but it is a one-trick-pony, and that trick is NOT classic rock. The Crunchbox gives very much a high gain JCM2000-type tone, with slightly scooped mids.
The last time I looked, "Classic Rock" describes 70's bands such as Free, Thin Lizzy, Black Sabbath, UFO etc.
Those bands basically use much lower gain tones, with NMV Marshalls and JCM800s, with much more mids than the CB can deliver.
Having owned a JTM45, a superlead, and a JCM800, I can say categorically that a Crunchbox sounds absolutely nothing like any of them. OK, rant over, I've got that off my chest.
For pedals, at the lower gain end of the classic rock spectrum, for me the Box of Rock is king - truly unbeatable.
Other pedals which can really nail some of those tone are the AC Booster (lower gain), and the BB pre-amp.
The Blackstar HT Dist and Dual can also pull off a number of those tones, in their own way.
I haven't played any of the Radial pedals, but know that some people rate them highly.
If I could justify the cost, I would get a Fetto (search for "Himmelstrutz Fetto")
In my experience, there are a bunch of "Marshall-clone" pedals out there, but very few of them actually respond in an amp-like manner, or give a particularly believable amp-like tone.
