The cleanest audio output we have seen
The HTC One S performance in our audio quality test came as a really pleasant surprise to us. It appears that the Beats influence hasn't been limited to a single equalizer preset this time as the smartphone delivers the cleanest output we have seen from any device so far.
When connected to an active external amplifier, the HTC One S audio is simply flawless - volume levels are a little above average and it got excellent scores on every part of our test.
What's most impressive though is the One S retains virtually the same performance when you plug in a pair of headphones. The stereo crosstalk takes the tiniest dip of any smartphone we've seen so far, while the rest of the readings are either totally unaffected or worsen by an undetectable amount. Volume levels remain the same too, so it's arguably the most impressive overall performance to date.
External Amplifier
Frequency Response: +0.13, -0.10
Noise Level: -91.0
Dynamic Range: 90.6
THD: 0.0089
IMD + Noise: 0.015
Stereo Crosstalk: -92.6
Headphones
(AKG, Unspecified model, 32ohms)
Frequency Response: +0.13, -0.04
Noise Level: -90.7
Dynamic Range: 90.6
THD: 0.011
IMD + Noise: 0.065
Stereo Crosstalk: -74.6