Hi Jag,
Ken is right. Unless you only want two channel, you're going to need a processor (Receiver) with pre-outs. I would very strongly discourage you from connecting an amplified signal into the line-level input of an amplifier. And I do not think it will be possible for you to set the separate speaker levels using your proposed methodology.
If you are REALLY committed to the expense and fidelity of separate amps, I don't think that it makes good sense to scrimp on the processor part. Any receiver from a reputable manufacturer that has pre-outs is going to have prodigious amounts of power. I'd start with the usual suspects (Denon 2805, Yamaha 1400, Onkyo 701?) and see when the "I want an amp" upgraditis hits.
