IFW

this doesn't tell me the sample rate, I have Flac files at various rates between 44kHz and 192kHz, depending on the output bitrate I choose I can control which files give audible errors, hence my belief that the issue is at least related to re-sampling

I have all EQ settings turned off at present.

same for me too, on my FIIO M6 Poweramp would give the best UI but can't provide the same quiality sound output as UAPP or FIIO Music - both of which output at the source bitrate without resampling etc..

what sample rates are the files you're playing? my suspicion is that resampling is just too much for the low power processor of the M6 and that ideally it would output at the sample rate of the file and just let the DAC deal with it.. should be lower power consumption too as the CPU wouldn't be dealing with resampling.

A quick update to this, I've done a lot more testing and found that the issue seems to be resampling, if I set the high res output to use the same sample rate as the file I'm playing then everything sounds great however if I pick a higher sample rate than the playing file then I get the crackling sounds. Obviously I could just set the sample rate to a low value but that somewhat defeats the point of using a DAP that is capable to handling high sample rates, is Poweramp every likely to support selecting the output sample rate to match the source files, within the limits of what the device supports and hence avoid the need to resample? I love the player for it's UI, library management and ease of use but if I can't utilise the capabilities of my DAP then I'll have to drop it for something else.

when listening to audio using the Hi-Res output on my Fiio M6 I have a faint popping/cracking noise in the background of all tracks, I've tried tweaking various settings from resampling, buffer sizes, disable the equaliser/tone control and enabling/disabling DVC. so far I've not managed to find a fix or work around. OpenSL ES output works fine but I'd prefer to use the Hi-Res output and utilise the onboard DAC (ES9018Q2C). For comparison the same audio tracks are fine when played through FIIO's default player, I'd rather use Poweramp though if possible due to the better UI, support for Album Artist tags and advanced shuffling etc.... Formats Tested: Flac 96KHz 24 bit Flac 44.1KHz 16 bit MP3 320 Kbps Audio Detection Log: 11:37:15.277 v3-build-860-uni Device: Android Samsung Electronics Co., Ltd. FiiO M6 m6 smdk7270 [armeabi-v7a, armeabi] reading=/system/etc/audio_policy.conf has outputs_primary, sampling_rates=44100|48000|88200|96000|176400|192000 has outputs/primary formats=AUDIO_FORMAT_PCM_16_BIT| AUDIO_FORMAT_PCM_8_24_BIT |AUDIO_FORMAT_PCM_24_BIT has primary sampling_rates=44100|48000|88200|96000|176400|192000 has primary formats=AUDIO_FORMAT_PCM_16_BIT| AUDIO_FORMAT_PCM_8_24_BIT |AUDIO_FORMAT_PCM_24_BIT has usb has usb outputs has usb_device, sampling_rates=48000 rate=48000 USB can handle Hi-Res - sdk=24 OK flags=0x900003400000000 FLAG_VARIANT_MIXED_HIRES FLAG_SUPPORTS_PCM_8_24 FLAG_SUPPORTS_USB FLAG_SUPPORTS_FLT_DYN_RANGE INTERNAL_OUTPUT_FLAG_SR_192K INTERNAL_OUTPUT_FLAG_SR_176K INTERNAL_OUTPUT_FLAG_SR_96K INTERNAL_OUTPUT_FLAG_SR_88K INTERNAL_OUTPUT_FLAG_SR_48K INTERNAL_OUTPUT_FLAG_SR_44K

I'm using Poweramp on a fiio M6, no issues with the license, I just bought a website, single device, license (doesn't matter whether the email is Google or not) and entered the email and license key into Poweramp (with a network connection)