I am fairly new to the audiophile scene. I have built up my music library on my macbook air with a few thousand high bit rate lossless songs and own a pair of sleek audio SA7 in ear monitors. I am not looking for any expensive, amazing setups but I'm aware that I can still increase the quality of my sound quite a bit. However, I am not sure whether I should buy an external DAC, an external sound card, a headphone amp, etc. and also whether I should get a USB or thunderbolt version of them. Can anyone recommend what addition I could get to increase my performance and possibly recommend some models?