[Nexus 6P Q&A, Help & Troubleshooting] hinxnz:
Latest version works well on 6p, I just pushed apk to priv-app and manually edited /vendor/etc/audio_effects.conf for v4a lib and effect, I personally wouldn't delete or rename it.

Also disabled musicfx and added supolicy exception.

Edit: okay just realized that effects aren't always kicking in, so also had to delete the deep_buffer entries in /system/etc/audio_policy.conf, now all working in normal mode.

How to:

Blue = Add entry

Red = Remove entry

/vendor/etc/audio_effects.conf

# List of effect libraries to load. Each library element must contain a "path" element
# giving the full path of the library .so file.
# libraries {
# <lib name> {
# path <lib path>
# }
# }
libraries {
[COLOR="Blue"] v4a_fx {
path /system/lib/soundfx/libv4a_fx_ics.so
}[/COLOR]
bundle {
path /system/lib/soundfx/libbundlewrapper.so
}
reverb {
path /system/lib/soundfx/libreverbwrapper.so
}
visualizer_sw {
path /system/lib/soundfx/libvisualizer.so
}
visualizer_hw {
path /system/lib/soundfx/libqcomvisualizer.so
}
fmas {
path /system/lib/soundfx/libfmas.so
}
proxy {
path /system/lib/soundfx/libeffectproxy.so
}
loudness_enhancer {
path /system/lib/soundfx/libldnhncr.so
}
offload_bundle {
path /system/lib/soundfx/libqcompostprocbundle.so
}
qcom_pre_processing {
path /system/lib/soundfx/libqcomvoiceprocessing.so
}
}

# Default pre-processing library. Add to audio_effect.conf "libraries" section if
# audio HAL implements support for default software audio pre-processing effects
#
# pre_processing {
# path /system/lib/soundfx/libaudiopreprocessing.so
# }

# list of effects to load. Each effect element must contain a "library" and a "uuid" element.
# The value of the "library" element must correspond to the name of one library element in the
# "libraries" element.
# The name of the effect element is indicative, only the value of the "uuid" element
# designates the effect.
# The uuid is the implementation specific UUID as specified by the effect vendor. This is not the
# generic effect type UUID.
# effects {
# <fx name> {
# library <lib name>
# uuid <effect uuid>
# }
# ...
# }

effects {
[COLOR="blue"] v4a_standard_fx {
library v4a_fx
uuid 41d3c987-e6cf-11e3-a88a-11aba5d5c51b
}
[/COLOR]
# additions for the proxy implementation
# Proxy implementation
#effectname {
#library proxy
#uuid xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx

# SW implemetation of the effect. Added as a node under the proxy to
# indicate this as a sub effect.
#libsw {
#library libSW
#uuid yyyyyyyy-yyyy-yyyy-yyyy-yyyyyyyyyyyy
#} End of SW effect

# HW implementation of the effect. Added as a node under the proxy to
# indicate this as a sub effect.
#libhw {
#library libHW
#uuid zzzzzzzz-zzzz-zzzz-zzzz-zzzzzzzzzzzz
#}End of HW effect
#} End of effect proxy

bassboost {
library proxy
uuid 14804144-a5ee-4d24-aa88-0002a5d5c51b

libsw {
library bundle
uuid 8631f300-72e2-11df-b57e-0002a5d5c51b
}

libhw {
library offload_bundle
uuid 2c4a8c24-1581-487f-94f6-0002a5d5c51b
}
}
virtualizer {
library fmas
uuid 36103c50-8514-11e2-9e96-0800200c9a66
}
equalizer {
library proxy
uuid c8e70ecd-48ca-456e-8a4f-0002a5d5c51b

libsw {
library bundle
uuid ce772f20-847d-11df-bb17-0002a5d5c51b
}

libhw {
library offload_bundle
uuid a0dac280-401c-11e3-9379-0002a5d5c51b
}
}
volume {
library bundle
uuid 119341a0-8469-11df-81f9-0002a5d5c51b
}
reverb_env_aux {
library proxy
uuid 48404ac9-d202-4ccc-bf84-0002a5d5c51b

libsw {
library reverb
uuid 4a387fc0-8ab3-11df-8bad-0002a5d5c51b
}

libhw {
library offload_bundle
uuid 79a18026-18fd-4185-8233-0002a5d5c51b
}
}
reverb_env_ins {
library proxy
uuid b707403a-a1c1-4291-9573-0002a5d5c51b

libsw {
library reverb
uuid c7a511a0-a3bb-11df-860e-0002a5d5c51b
}

libhw {
library offload_bundle
uuid eb64ea04-973b-43d2-8f5e-0002a5d5c51b
}
}
reverb_pre_aux {
library proxy
uuid 1b78f587-6d1c-422e-8b84-0002a5d5c51b

libsw {
library reverb
uuid f29a1400-a3bb-11df-8ddc-0002a5d5c51b
}

libhw {
library offload_bundle
uuid 6987be09-b142-4b41-9056-0002a5d5c51b
}
}
reverb_pre_ins {
library proxy
uuid f3e178d2-ebcb-408e-8357-0002a5d5c51b

libsw {
library reverb
uuid 172cdf00-a3bc-11df-a72f-0002a5d5c51b
}

libhw {
library offload_bundle
uuid aa2bebf6-47cf-4613-9bca-0002a5d5c51b
}
}
visualizer {
library proxy
uuid ec7178ec-e5e1-4432-a3f4-4657e6795210

libsw {
library visualizer_sw
uuid d069d9e0-8329-11df-9168-0002a5d5c51b
}

libhw {
library visualizer_hw
uuid 7a8044a0-1a71-11e3-a184-0002a5d5c51b
}
}
downmix {
library fmas
uuid 36103c51-8514-11e2-9e96-0800200c9a66
}
loudness_enhancer {
library loudness_enhancer
uuid fa415329-2034-4bea-b5dc-5b381c8d1e2c
}
aec {
library qcom_pre_processing
uuid dce45980-42b3-11e5-89be-0002a5d5c51b
}
ns {
library qcom_pre_processing
uuid effd4400-42b3-11e5-a2be-0002a5d5c51b
}
}

# Default pre-processing effects. Add to audio_effect.conf "effects" section if
# audio HAL implements support for them.
#
# agc {
# library pre_processing
# uuid aa8130e0-66fc-11e0-bad0-0002a5d5c51b
# }
# aec {
# library pre_processing
# uuid bb392ec0-8d4d-11e0-a896-0002a5d5c51b
# }
# ns {
# library pre_processing
# uuid c06c8400-8e06-11e0-9cb6-0002a5d5c51b
# }

# Audio preprocessor configurations.
# The pre processor configuration consists in a list of elements each describing
# pre processor settings for a given input source. Valid input source names are:
# "mic", "camcorder", "voice_recognition", "voice_communication"
# Each input source element contains a list of effects elements. The name of the effect
# element must be the name of one of the effects in the "effects" list of the file.
# Each effect element may optionally contain a list of parameters and their
# default value to apply when the pre processor effect is created.
# A parameter is defined by a "param" element and a "value" element. Each of these elements
# consists in one or more elements specifying a type followed by a value.
# The types defined are: "int", "short", "float", "bool" and "string"
# When both "param" and "value" are a single int, a simple form is allowed where just
# the param and value pair is present in the parameter description
# pre_processing {
# <input source name> {
# <fx name> {
# <param 1 name> {
# param {
# int|short|float|bool|string <value>
# [ int|short|float|bool|string <value> ]
# ...
# }
# value {
# int|short|float|bool|string <value>
# [ int|short|float|bool|string <value> ]
# ...
# }
# }
# <param 2 name > {<param> <value>}
# ...
# }
# ...
# }
# ...
# }

pre_processing {
voice_communication {
aec {
}
ns {
}
}
}

/system/etc/audio_policy.conf

# Global configuration section:
# - lists input and output devices always present on the device
# as well as the output device selected by default.
# Devices are designated by a string that corresponds to the enum in audio.h
# - defines whether the speaker output path uses DRC
# "TRUE" means DRC is enabled, "FALSE" or omission means DRC isn't used.

global_configuration {
attached_output_devices AUDIO_DEVICE_OUT_EARPIECE|AUDIO_DEVICE_OUT_SPEAKER|AUDIO_DEVICE_OUT_TELEPHONY_TX
default_output_device AUDIO_DEVICE_OUT_SPEAKER
attached_input_devices AUDIO_DEVICE_IN_BUILTIN_MIC|AUDIO_DEVICE_IN_BACK_MIC|AUDIO_DEVICE_IN_REMOTE_SUBMIX|AUDIO_DEVICE_IN_TELEPHONY_RX
speaker_drc_enabled TRUE
}

# audio hardware module section: contains descriptors for all audio hw modules present on the
# device. Each hw module node is named after the corresponding hw module library base name.
# For instance, "primary" corresponds to audio.primary.<device>.so.
# The "primary" module is mandatory and must include at least one output with
# AUDIO_OUTPUT_FLAG_PRIMARY flag.
# Each module descriptor contains one or more output profile descriptors and zero or more
# input profile descriptors. Each profile lists all the parameters supported by a given output
# or input stream category.
# The "channel_masks", "formats", "devices" and "flags" are specified using strings corresponding
# to enums in audio.h and audio_policy.h. They are concatenated by use of "|" without space or "\n".

audio_hw_modules {
primary {
outputs {
primary {
sampling_rates 44100|48000
channel_masks AUDIO_CHANNEL_OUT_STEREO
formats AUDIO_FORMAT_PCM_16_BIT
devices AUDIO_DEVICE_OUT_EARPIECE|AUDIO_DEVICE_OUT_SPEAKER|AUDIO_DEVICE_OUT_WIRED_HEADSET|AUDIO_DEVICE_OUT_WIRED_HEADPHONE|AUDIO_DEVICE_OUT_LINE|AUDIO_DEVICE_OUT_ALL_SCO
flags AUDIO_OUTPUT_FLAG_FAST|AUDIO_OUTPUT_FLAG_PRIMARY
}
raw {
sampling_rates 48000
channel_masks AUDIO_CHANNEL_OUT_STEREO
formats AUDIO_FORMAT_PCM_16_BIT
devices AUDIO_DEVICE_OUT_EARPIECE|AUDIO_DEVICE_OUT_SPEAKER|AUDIO_DEVICE_OUT_WIRED_HEADSET|AUDIO_DEVICE_OUT_WIRED_HEADPHONE|AUDIO_DEVICE_OUT_LINE|AUDIO_DEVICE_OUT_ALL_SCO
flags AUDIO_OUTPUT_FLAG_FAST|AUDIO_OUTPUT_FLAG_RAW
}
[COLOR="Red"] deep_buffer {
sampling_rates 8000|11025|12000|16000|22050|24000|32000|44100|48000
channel_masks AUDIO_CHANNEL_OUT_STEREO
formats AUDIO_FORMAT_PCM_16_BIT
devices AUDIO_DEVICE_OUT_SPEAKER|AUDIO_DEVICE_OUT_EARPIECE|AUDIO_DEVICE_OUT_WIRED_HEADSET|AUDIO_DEVICE_OUT_WIRED_HEADPHONE|AUDIO_DEVICE_OUT_LINE|AUDIO_DEVICE_OUT_ALL_SCO
flags AUDIO_OUTPUT_FLAG_DEEP_BUFFER
}[/COLOR]
compress_offload {
sampling_rates 8000|11025|12000|16000|22050|24000|32000|44100|48000
channel_masks AUDIO_CHANNEL_OUT_MONO|AUDIO_CHANNEL_OUT_STEREO
formats AUDIO_FORMAT_MP3|AUDIO_FORMAT_AAC_LC|AUDIO_FORMAT_AAC_HE_V1|AUDIO_FORMAT_AAC_HE_V2
devices AUDIO_DEVICE_OUT_SPEAKER|AUDIO_DEVICE_OUT_WIRED_HEADSET|AUDIO_DEVICE_OUT_WIRED_HEADPHONE|AUDIO_DEVICE_OUT_LINE
flags AUDIO_OUTPUT_FLAG_DIRECT|AUDIO_OUTPUT_FLAG_COMPRESS_OFFLOAD|AUDIO_OUTPUT_FLAG_NON_BLOCKING
}
voice_tx {
sampling_rates 8000|16000|48000
channel_masks AUDIO_CHANNEL_OUT_STEREO|AUDIO_CHANNEL_OUT_MONO
formats AUDIO_FORMAT_PCM_16_BIT
devices AUDIO_DEVICE_OUT_TELEPHONY_TX
}
tts {
sampling_rates 48000
channel_masks AUDIO_CHANNEL_OUT_STEREO
formats AUDIO_FORMAT_PCM_16_BIT
devices AUDIO_DEVICE_OUT_SPEAKER
flags AUDIO_OUTPUT_FLAG_TTS
}
}
inputs {
primary {
sampling_rates 8000|11025|12000|16000|22050|24000|32000|44100|48000
channel_masks AUDIO_CHANNEL_IN_MONO|AUDIO_CHANNEL_IN_STEREO|AUDIO_CHANNEL_IN_FRONT_BACK|AUDIO_CHANNEL_INDEX_MASK_3
formats AUDIO_FORMAT_PCM_16_BIT
devices AUDIO_DEVICE_IN_BUILTIN_MIC|AUDIO_DEVICE_IN_WIRED_HEADSET|AUDIO_DEVICE_IN_BLUETOOTH_SCO_HEADSET|AUDIO_DEVICE_IN_VOICE_CALL|AUDIO_DEVICE_IN_BACK_MIC
}
voice_rx {
sampling_rates 8000|16000|48000
channel_masks AUDIO_CHANNEL_IN_STEREO|AUDIO_CHANNEL_IN_MONO
formats AUDIO_FORMAT_PCM_16_BIT
devices AUDIO_DEVICE_IN_TELEPHONY_RX
}
}
}
a2dp {
outputs {
a2dp {
sampling_rates 44100
channel_masks AUDIO_CHANNEL_OUT_STEREO
formats AUDIO_FORMAT_PCM_16_BIT
devices AUDIO_DEVICE_OUT_ALL_A2DP
}
}
inputs {
a2dp {
sampling_rates 44100|48000
channel_masks AUDIO_CHANNEL_IN_MONO|AUDIO_CHANNEL_IN_STEREO
formats AUDIO_FORMAT_PCM_16_BIT
devices AUDIO_DEVICE_IN_BLUETOOTH_A2DP
}
}
}
usb {
outputs {
usb_accessory {
sampling_rates 44100
channel_masks AUDIO_CHANNEL_OUT_STEREO
formats AUDIO_FORMAT_PCM_16_BIT
devices AUDIO_DEVICE_OUT_USB_ACCESSORY
}
usb_device {
sampling_rates dynamic
channel_masks dynamic
formats dynamic
devices AUDIO_DEVICE_OUT_USB_DEVICE
}
}
inputs {
usb_device {
sampling_rates dynamic
channel_masks dynamic
formats dynamic
devices AUDIO_DEVICE_IN_USB_DEVICE
}
}
}
r_submix {
outputs {
submix {
sampling_rates 48000
channel_masks AUDIO_CHANNEL_OUT_STEREO
formats AUDIO_FORMAT_PCM_16_BIT
devices AUDIO_DEVICE_OUT_REMOTE_SUBMIX
}
}
inputs {
submix {
sampling_rates 48000
channel_masks AUDIO_CHANNEL_IN_STEREO
formats AUDIO_FORMAT_PCM_16_BIT
devices AUDIO_DEVICE_IN_REMOTE_SUBMIX
}
}
}
}