My friends sellin me an early 80s twin reverb for 500. I currently have an vox AD50, and I was thinkin that it was a great deal. Recently though, I read that early 80's Fender amps lacked quality of their earlier and later models. Is this true?

Also, I read that the Big muff sounds good on the twin, yet when I played the model at Guitar center, it sounded like the speaker was distorting, except in the bad way (as in breaking up). I read Jack White uses a Big mUff with his twin (regardless of whether you like him or not, as I dont really care for him), and his distortion sounds very full.
I wouldn't go for it. You can get a much nicer 60's Blackface amp for around that price.

And what's bad about speaker breakup?
Speaker breakup is awesome.

A pedal shouldn't make the speaker break up, you might just not like the tone of the muff.
I'm not very active here on UG currently.
I'm a retired Supermod off to the greener pastures of the real world.
I checked out ebay, and the lowest price for a vintage was around 900+, and I really dont have the extra money.

Also, I love the sound of the big muff, but it sounded very different on the twin i played (a 65 reissue)