Yep, really subjective topic... Though S4 mini's sound quality isn't that great, so pointless to spent a fortune on headphone. Sennheiser CX 300 II price has come down a lot since its launch (like US$ 37@Amazon), I would grab a set of those. Though S4 mini may not be a good match up, it will reveal the poor sound quality. There's a super low impedance easy drive Yamaha I have which will cover the lack of mid-low frequency of S4 mini, but I can't find my set right now, will let you know the model if I find it.