It's not the best way to do this but you can take the speaker level input and plug it into the input of a new amp. You MUST have a speaker to line level adapter or have an amp that's made to take speaker level as an input. If you want to go this route, I have an adapter I'll send you for $15 shipped.

I personally think that YOU will be happy with either round or oval (6x9 or otherwise) speakers. Other people might not be satisfied until they have a set of McIntosh's in their car (ie me).