Wireless doesn't affect sound quality IF you have a decent DAC that properly reclocks. (These days, most of them do, and you're more likely to find a bad one at the top end of the price chain.) AE straight into your amp is not a good idea if this is going to be your primary source. It's fine for casual listening or already-compressed Internet streams.
If you already own a transport, I wouldn't bother using a Mac for that purpose.
If you already own a transport, I wouldn't bother using a Mac for that purpose.