RPi3 / Screen / HiFiBerry Dac+ Pro Questions

Hi All,

I’m relatively new the the RPI but am really enjoying the experience, and recently bought HiFiBerry Dac+ Pro. I have mounted my RPi3 on the official 7inch touchscreen, then mounted the Dac+ Pro on top.

I am currently powering the RPi, the Screen and the DAC using the official RPi 5v power supply. I have powered the DAC by soldering the red and black wires to to the first and fourth pins (Like this: [list=]http://cdn.instructables.com/FC4/3NEZ/IEX4QVKA/FC43NEZIEX4QVKA.LARGE.jpg[/list] but soldered on, rather than jumpers. ) I have updated config.txt and the DAC is now playing music beautifully through OpenElec/Kodi (I’ll explore other Music player solutions later - just used Kodi as i already had a working copy install).

I would now like to improve sound quality by removing the R14 resistorr and power the analogue circuits on the DAC using a battery back recommended on another forum (liner PSU is too expensive at this early stage) - https://www.amazon.co.uk/gp/product/B00FAU7ZB2/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

I have four questions (apologies for my newbie ignorance) (if you can only help with one or two of them, I’d appreciate anything you can advice me!) :

  1. When the online guides to performing this upgrade to the Dac+ Pro says ‘connect your external 5V power supply to the pin header P3 (left GND, right +5V)’, does this mean solder the wires onto the metal the edge of the hole? I’m new to soldering but when soldering the red and whtie wires to power the DAC, there were posts to connect them to, and I just want to check if it’s the same when there’s only a hole.

  2. I currently have the DAC, screen and PI powered by an official RPi 5v power supply, connected to the micro USB socket on the RPi (and using the jumper cables mentioned above). If i carry out this modification to power the the DAc’s analogue circuits from the battery pack with my power arranged in this way, will I actually be bypasing using he USB power supply for the analgue circuits as I intend?

  3. I am playing my music as Wavs from a 4tb USB drive powerered solely from the USB socket on the RPi (and it powers and plays fine, currently), will I get better sound quality and/or remove USB interference (as well as reducing problems from power-drain on the RPi power supply) if i connect a double USB lead to the 4tb drive? The power connected could also go into the battery pack, whilst the data connected still going into the RPi? Or would this make no difference to sound (or power-drain, as the systems is currently working fine with the RPi powering the HD?)

  4. Finally. when I’m soldering wires from the battery pack onto the edges of the appropriate holes on DAC, do I simply cut the micro-connector off the end of the normal USB charging lead the comes with the battery back and strip the wires? Also, if I do this, how do I know which wire is grnd and which is 5v? Is the stripped USB cable likely to be black and red inside?

Again, my apologies for any newbie ignorance!

Many thanks,