i have to choose between these three sets, any advice would help a ton.   a set of KRKs together ends up right around 300-350 as do a set of Audioengine A5's   now the from what i read, the Swans are rather new.   I'll be mainly using these just for listening to music, and having...

so yes, i am COMPLETELY new at this im not sure exactly what i need, some people are saying a DAC? anyways i need something to make my sound a lot better.. obviously it would be with USB..but from a mac i need the output to be 3.5mm or a 1/4 AND RCA i was looking at something like...