Sibilance

I noted the comment blaming it on speaker response in the 3 kHz area. That's often near the crossover to tweeters. And crossovers can be crazy. A speaker can be flat in the crossover region but if the transfer function(shape of the roll offs at crossover) are not 'nice' then there can be ringing in that area which will sound sibilant even though the measure response is flat there.

Vibration was mentioned earlier. Are your components isolated from your rack/furniture? Are you using any footers to decouple or drain vibration from the components?

My system suffered from harsh highs on many digital tracks, CDs and streaming. It took me awhile to find that the DAC was vibrating on it's shelf. I was using aftermarket footers but they weren't good enough to stop the vibration of the DAC. 

I noticed the same harshness on my system ( $ 12,000) until the Ares 2 DAC was introduced into the mix. A good quality R2R DAC would help you and really open up the soundstage on recordings from Pink Floyd.

If you're using the Node2i's internal Dac, then I agree with buddyboy. Adding a standalone DAC will improve SQ in every way. A R2R multibit has a more forgiving presentation.

Preamp has isolators not cd player (short of what was provided stock) or Bluesound 2i.