If you're serious about sound and have the headphones or speakers to match, a portable DAC is a serious audio upgrade. Of course you could just get used to how your phone, tablet or computer plays music. But if you're an audiophile (or even if you shy away from that term but you just love music) that just won't do. So, if your music isn't sounding quite as spectacular as it should – and the only thing you've changed recently is the source – it's likely that your new device (a new laptop, desktop, phone or tablet) has a poor quality DAC built-in. The second reason to shell out for a better system is the fact that some of the more premium headphones on the market are 'high-impedance' headphones, which require more power through the headphone jack on your music source in order to work properly. (Impedance, for the record, is measured in a unit called ohms, and less than 50 ohms is considered to be low-impedance.) As a rule, the harder a pair of headphones need to be driven, the better they will eventually sound when paired with the right equipment. An external DAC helps with these headphones as it can work as a headphone amp to provide the extra power needed to drive a high-impedance pair of 'phones.