You guys need to try PowerAMP this time. Walkman app is good because it supports ClearAudio+ plus ClearStereo for headphone and ClearPhase plus XLOUD for speaker. However, some apps like PowerAMP does also support all of them and provides same and even better audio quality.
I usually use PowerAMP EQ plus Sony EQ at the same time. They worked together perfectly, you guys just need to get in PowerAMP's Tone/Vol, long press on MusicFX and you can now access to the Sony EQ menu just like in Walkman app, there you can find ClearAudio+, ClearStereo, ClearPhase, XLOUD and also a Dynamic normaliser for loudness volume boost.
My z1c audio quality indeed is good but just the only problem to me is Sony EQ doesn't working very well(but it is acceptable) with my Beats earphone from HTC. They are mainly tuned for Sony's own ear/headphone because I've tested it myself in a local Sony Store(they have put every Sony earphone out and let customer to try). I will need HTC's beats EQ profile to real match my earphone but I have no time to do such mod myself, so I use back my HTC to listen music....lol