JustAnAudiophileNo amp or DAC increases the quality of the headphone.
I think you mean to ask is whether it's a better DAC/amp than your current computer/mobile device. Let us know what your source is and we can help more. Can't really say without that but if you're going from a crappy/noisy sound card then the answer is probably to definitely.
justex07Well, not technically no, but that's also obviously not the intended question. But to really answer the question, we'd need to know what setup they have, if they're going straight off a phone, pc, etc.
JustAnAudiophileThen IF the IDOL works on the 5s, yes by way of more power. However, the FiiO K1 (similar device but obviously not exactly the same) seems to only work with the iPhone 6+/s+. I tried it with the iPhone 5, 5s, 6 and the iPadAir and none of them worked with the K1.
So I'd make sure the IDOL is compatible first but if it is, and if it is as good or better than the FiiOK1, I can confirm its better than the stock output.