Node 2i performance suggestions pls

Yes, C7 is the PC type. No IEC connector, it's called a figure 8.

You probably know this, a good cable to the DAC is vital. I use SPDIF coax.

I had a great cable going from my Node 2i to my older modded Meitner DAC, but in the end I am satisfied just using the DAC in the 2i.  

I really love this little streamer, it doesn't owe me a thing. This is a bit embarrassing, but the first internet radio station I tuned into was called "radio 10, 60's & 70's hits".  I haven't had any desire whatsoever to change the channel.  The sound quality is just fine for me for listening hours on end.  So many tunes that I love as if I were programming the channel.

The biggest difference that I noticed cable wise on my Node 2i was running CAT8 cable to it from my switch.  I just used generic cable but I'm sure Supra, Wireworld etc would be even better.

It definitely fleshed out the sound, I noticed a much bigger difference versus upgrading the power cable(Shunyata Venom 3).  

I ordered the Supra CAT8 last week waiting for delivery.

The biggest upgrade I did to my Node 2 was replacing it with a TEAC NT-505.  Other than that, using a better external DAC (I was using my Auralic Vega) can improve sound quality.  I tried a Pangea power cable (really heavy, no difference in sound quality) and Cat 6 cables (no noticeable difference).