As in the title, what do you think would sound better, uniti atom headphone edition or headline fed from ndx2/282/hc dr?
These are two non-overlapping price categories.
What headphones will you be using?
I would imagine the headline fed from your 282 with NDX2 as source would out-pace the Atom HE.
Additionally, any analog input into the HE is converted to digital then uses the internal DAC, making analog input from the 282 less effective.
That being said, the HE can drive more difficult headphones than the Headline can.
You’d want to get a stand-alone power supply for the Headline, as well.
Having heard the Headline with various power supplies, I believe the answer might depend on which PSU you connect to it. IMHO Headline becomes great with a HiCap, and is truly amazing with a SuperCap. You cannot use that same HC or SC for powering the 282.
Cost performance wise, the Headline will be fed from a superior source and if fed from a good power supply, be a superior headphone amp irrespictive of the single ended output.
Of course, if remote control or cable lengths are an issue, the Atom HE might be functionally preferable. I’d hunt for second hand bits. A used HL2/HCdr would be a bargain. Of course, if you aren’t married to Naim, there are other superb options available.