The NX2s datasheet shows that the response is flat to 20Hz, so there doesn't appear to be an issue to address. It's possible that Topping went with undersized coupling caps in the NX1s due to lack of space. I wonder if they were also happy for the more expensive units to have better bass ;-)

Good work, glad I could help mate. Do you notice a difference? Keen for someone to compare a modded NX1S with an NX3.... :-)

No - the two channels need to be kept separate

You connect the two legs of both caps (one wire link between the legs of C33 and one wire link between the legs of C34)

I left the caps in place and soldered a thin wire from one pin to the other (to short them out of the circuit). I actually used the legs of two spare resistors, as it was easy to tin one leg with solder, hold in place and then solder to the existing cap legs (then trim off the resistor body and...

I received my NX1s today. Looking at Toppings frequency response graph the bass is >2db down at 20Hz. Sure enough this appears to be largely due to undersized coupling caps between the volume pot and gain stage (1uF into 9.4Khz resulting in a -3db point of 16.9Hz). The good news is that there is...

My music is on a NAS. For whatever reason the small Edimax USB wifi device didn't provide a stable connection (it does with same RPi running Volumio and playing 24/96 waves) so I have a wired network connection to an Airport Express, acting as wireless bridge to my router.

In case anyone is interested, the M8 works perfectly with an Rpi2 running Rune Audio (http://www.runeaudio.com/). DSD playback works perfectly - DoP can be activated in the settings.

Can anyone help me to identify all of the coupling caps in the zero? I've swapped over to OPA627 + 2xLM4562, cut out the 4x ceramic caps and now I want to turn my attention to the caps in the signal path.... :-)