parasound 3500 verses parasond jc1

Apart from being differently boxed (as you note) they're NOT supposed to be identical circuits, either. They have a site that talks about that.
As to what differences you'll hear -- in simplistic terms, the JC1 simply sound better in all respects... (IMO)
BTW, why don't you like your present amp?
Cheers

I do ,im wondering if i should buy another 3500 for byamp or the jc1s

Having just read the review of the original 3500 from 5 years ago, they say the bass is its strong suit and the mids and highes are where the improveent should be.(Jan.00)