MitchRussoPick up an Apogee One or a similar DAC. Apogee's A/D converter's are pretty well renowned. 250 for the first gen (which is mac compatible), 350 for the 2nd gen (Mac +iOS).
MitchRussoMy recommendation for a high-quality audio setup is to use a decent microphone with a good audio interface, which must be able to supply the 48V phantom power. I just bought the MXL bundle with the 990 and 991 condenser microphones, and connected to my Native Instruments interface they sound great for a home studio.
MitchRussoGet a Focusrite interface my friend. I have a Scarlett. Best bang for your buck IMO, excelent preamps. The brand was funded and still owned by Rupert Neve, an indisputable legend of the pro audio industry. It also comes with great FX plug ins, supports OS X and there´s even a firmware that enables IPad compatibility.