Atom as preamp only

When you say 'fronting' a higher spec system, I presume you mean as a digital source as well as a preamp? In which case, the difference between that and a 282 fronted by an NDX is huge. Hard to be more specific, the differences are there across the board, as you would expect when one solution costs several times as much as the other.

I had an Atom running through a NAP 200, I thought it sounded pretty good until I tried a NAC 202 in its place, the 202 blew it out of the water, and that was still using the atom purely as a streamer. There was so much more detail and a more enjoyable sound. Recently upgraded to an NDX2, with the 202 and 200 another huge leap in sound quality.

OK thanks, was looking for a way to bring hdmi , digital, streaming and LP12 together feeding an active xover. Looks like the Atom may fall short . 

How important is the HDMI input in all this? Only the new Unitis have HDMI ARC, and in practice it has not always been reliable so far. It seems that this is partly due to poor implementation by TV manufacturers, so a simple Toslink connection can be a better option. This might open the door to other options with better sound quality.