Sound Quality Issues with IQAudio PI-DAC+

I ordered a raspberry pi 2 B and a IQAudio Pi-DAC+ (on behalf of Santa and my wife) early December and finally got to unwrap it and play with it on the 25th. I’ve tried several versions of Volumio and RuneAudio now and in every case the sound from the headphones comes out distorted. I spent a couple of days now scouring forums for answers but every suggestion I try results in the same distorted sound.

I’ve tried several distributions from here and the official volumio and rune audio sites.

If you can spot anything amiss or have any suggestions then thanks in advance, otherwise I’ll assume I just got unlucky and received a faulty one and start the returns process.

My set up currently comprises.

Official Pi 2A PSU
Raspberry Pi 2 model b
IQaudio DAC+ hat
Sandisk ultra 16GB micro SD
Sandisk ultra 64GB USB3 memory stick
Sennheiser HD429 headphones

The alsamixer settings are as follows

I’m currently using runeaudio (this version I believe - RuneAudio_rpi2_0.3-beta_20150304_2GB) and here’s the debug output.

System info

Linux version 3.18.7-3-ARCH (builduser@leming) (gcc version 4.9.2 20141224 (prerelease) (GCC) ) #1 SMP PREEMPT Fri Feb 13 06:23:21 MST 2015

system time: Mon Dec 28 13:42:05 CET 2015

system load: 0.31 0.11 0.04 4/142 683

HW platform: RaspberryPi2 (08)

playerID: 08b26fff2ac4ddac6fee7fbbc1890504ae

due to post size limits

So it appears that this is an issue with the headphone amp or the configuration of it as I’ve just plugged this into my hifi via the phono connectors and … WOW!

I’ll focus on resolving that once I’ve listened to my entire music collection again. :-)

If anyone is considering a raspberry pi and DAC hat as a replacement for an old CD front-end then go for it. I don’t think you’ll be disappointed.

Is it possible you were just over-driving the headphones causing them to clip/distort with the amp?