Raspberry Pi 3 – Intermittent skipping on high quality audio

Hi everyone,

I recently got myself a Raspberry Pi and installed OpenElec /Kodi 16 on it. I also have some high resolution FLAC audio (surround) which I have been playing via the Pi and my Denon receiver connected via HDMI.
If I play the audio via a usb key – then there are no issues. But recently I got a 3TB seagate expansion hard drive. The hard drive is connected to the Pi via a 5V 4A powered USB hub. The only other used USB slot on the Pi is for a bluetooth dongle for a thumb keyboard.

Problem is: music keeps skipping every few seconds – making it unlistenable. Is this possibly because the hard drive isn’t fast enough (5400 RPM) to supply the high bandwidth audio files?

Any ideas if this can be rectified via an advanced settings file or changing the setup a little bit? Or any other suggestions?