MC 402 vs. MC 7300

Depends on the speakers that you are driving. I run a C45 into an MC402 into a pair of B&W 803's without ever approaching the limits of the amp while pushing the speakers about as far as they'll go. Other than available power, the Mcintosh ss amps sound remarkably similar. I doubt that anyone could tell the difference between a 402, 252, pair of 501's, or an integrated unless the current limitations are reached.

Winger - Upgrade the amp before upgrading the preamp. The amp has a more difficult job to do - driving a difficult load. The signal levels fed to the preamp just aren't that difficult to deal with - particularly if you are feeding a signal from a cdp. In short, getting the amp right is a harder design task when it comes to home audio. There is the school of thought garbage in garbage out - profferred by those who recomend upgrading a preamp first - that approach is inapplicable for this scenario.

Back to your original question - I am unaware of an amplifier currently made by Mcintosh with a model number of 7300. There is the 6300 and the 7000. As to driving the MS5 with these different models, The 6300 would be a light, the 7000 will likely work fine for all but the loudest listening levels, but at those levels, my guess is that you will get the power guard to flicker. The 402 would be my choice.