[OnePlus X Themes and Apps] etoy:
logcat is all about this:

E/WavesFX_MaxxAudioQualcomm.cpp( 6128): /home/builder/build_env/Consumer/MainRel/Consumer/Platform/Android/Applications/WavesFXSeviceLib/jni/../../../Alg/Qualcomm/..//Qualcomm/MSM8974//WavesFX_MaxxAudioQualcomm.cpp:711,
E/WavesFX_MaxxAudioQualcomm.cpp( 6128): Error: cannot find Wave device in topology! 199
E/WavesFX_MaxxAudioQualcomm.cpp( 6128): /home/builder/build_env/Consumer/MainRel/Consumer/Platform/Android/Applications/WavesFXSeviceLib/jni/../../../Alg/Qualcomm/..//Qualcomm/MSM8974//WavesFX_MaxxAudioQualcomm.cpp:711,
E/WavesFX_MaxxAudioQualcomm.cpp( 6128): Error: cannot find Wave device in topology! 199
E/WavesFX_MaxxAudioQualcomm.cpp( 6128): /home/builder/build_env/Consumer/MainRel/Consumer/Platform/Android/Applications/WavesFXSeviceLib/jni/../../../Alg/Qualcomm/..//Qualcomm/MSM8974//WavesFX_MaxxAudioQualcomm.cpp:711,
E/WavesFX_MaxxAudioQualcomm.cpp( 6128): Error: cannot find Wave device in topology! 199
E/WavesFX_MaxxAudioQualcomm.cpp( 6128): /home/builder/build_env/Consumer/MainRel/Consumer/Platform/Android/Applications/WavesFXSeviceLib/jni/../../../Alg/Qualcomm/..//Qualcomm/MSM8974//WavesFX_MaxxAudioQualcomm.cpp:711,
E/WavesFX_MaxxAudioQualcomm.cpp( 6128): Error: cannot find Wave device in topology! 199
E/WavesFX_MaxxAudioQualcomm.cpp( 6128): /home/builder/build_env/Consumer/MainRel/Consumer/Platform/Android/Applications/WavesFXSeviceLib/jni/../../../Alg/Qualcomm/..//Qualcomm/MSM8974//WavesFX_MaxxAudioQualcomm.cpp:711,
E/WavesFX_MaxxAudioQualcomm.cpp( 6128): Error: cannot find Wave device in topology! 199
D/ConnectivityService( 934): notifyType CAP_CHANGED for NetworkAgentInfo [WIFI () - 101]
E/WavesFX_MaxxAudioQualcomm.cpp( 6128): /home/builder/build_env/Consumer/MainRel/Consumer/Platform/Android/Applications/WavesFXSeviceLib/jni/../../../Alg/Qualcomm/..//Qualcomm/MSM8974//WavesFX_MaxxAudioQualcomm.cpp:711,
E/WavesFX_MaxxAudioQualcomm.cpp( 6128): Error: cannot find Wave device in topology! 199
E/WavesFX_MaxxAudioQualcomm.cpp( 6128): /home/builder/build_env/Consumer/MainRel/Consumer/Platform/Android/Applications/WavesFXSeviceLib/jni/../../../Alg/Qualcomm/..//Qualcomm/MSM8974//WavesFX_MaxxAudioQualcomm.cpp:711,
E/WavesFX_MaxxAudioQualcomm.cpp( 6128): Error: cannot find Wave device in topology! 199
E/WavesFX_MaxxAudioQualcomm.cpp( 6128): /home/builder/build_env/Consumer/MainRel/Consumer/Platform/Android/Applications/WavesFXSeviceLib/jni/../../../Alg/Qualcomm/..//Qualcomm/MSM8974//WavesFX_MaxxAudioQualcomm.cpp:711,
E/WavesFX_MaxxAudioQualcomm.cpp( 6128): Error: cannot find Wave device in topology! 199
E/WavesFX_MaxxAudioQualcomm.cpp( 6128): /home/builder/build_env/Consumer/MainRel/Consumer/Platform/Android/Applications/WavesFXSeviceLib/jni/../../../Alg/Qualcomm/..//Qualcomm/MSM8974//WavesFX_MaxxAudioQualcomm.cpp:711,
E/WavesFX_MaxxAudioQualcomm.cpp( 6128): Error: cannot find Wave device in topology! 199
E/WavesFX_MaxxAudioQualcomm.cpp( 6128): /home/builder/build_env/Consumer/MainRel/Consumer/Platform/Android/Applications/WavesFXSeviceLib/jni/../../../Alg/Qualcomm/..//Qualcomm/MSM8974//WavesFX_MaxxAudioQualcomm.cpp:711,
E/WavesFX_MaxxAudioQualcomm.cpp( 6128): Error: cannot find Wave device in topology! 199

edit: good news (sort of), i flashed the c-apps package over maxxaudio and it now partially works. no eq but some of the effect knobs below are now working. that should be a good start point maybe