Both Samsung Galaxy S4 versions did greatly in our audio quality test. They both had excellently clean output in both testing scenarios and despite the fact that they use different audio chips, their output is quite hard to tell apart.
The Qualcomm-powered Samsung I9505 Galaxy S4 had the tinniest of edges in the headphones-plugged-in testing scenario, exhibiting slightly cleaner audio output, but we doubt anyone will be able to hear the difference. The Exynos-packing I9500 Galaxy S4 makes up for it with an advantage that's a bit easier to hear on your own - slightly higher maximum volume levels.
No matter which of the versions of the Samsung flagship you choose, you will be more than happy with its output and certainly we wouldn't advise you to make your selection based on the audio output - it's just that it's too close to call here.
And here go the results so you can see for yourselves.
|Test||Frequency response||Noise level||Dynamic range||THD||IMD + Noise||Stereo crosstalk|
|Samsung I9500 Galaxy S4||+0.03, -0.04||-94.5||93.4||0.0036||0.016||-93.0|
|Samsung I9500 Galaxy S4 (headphones attached)||+0.03, -0.02||-93.0||92.9||0.0084||0.062||-77.5|
|Samsung I9505 Galaxy S4||+0.03, -0.08||-95.9||93.2||0.0030||0.0092||-96.4|
|Samsung I9505 Galaxy S4 (headphones attached)||+0.03, -0.08||-96.0||93.3||0.0031||0.089||-77.5|
Samsung I9500 Galaxy S4 frequency response
Samsung Galaxy S4 frequency response
You can learn more about the whole testing process here.