Sony HAP-Z1ES Hi-Res Music Player RMAF 2013

Mitch4t is correct. You cannot use it "just" as a DAC although it contains one.

.
It's easy, just go to the Sony website and see photos of the rear of the unit yourself. No inputs.

There is no mention of it being able to function as a DAC for an external transport or other sources.
.

Duh, it seems I was having another one of my brain farts. Thanks Mitch/Kal for the clarification.

What is bizarre is the the Sony HAP S1 at $1000 (as opposed to the Z1ES at $2000) has a whole range of inputs: coax, optical, line, ethernet and includes a 40 W amp section or can be used as a DAC with a Line Out. The only benefit of the Z1 is a 1TB HD vs 500GB in the S1 and balanced outputs. Furthermore the codecs seem identical in both. Why would anyone purchase the Z1 at twice the price??

As near as I can tell from the published specs, the feature that looks to be the most responsible for the price difference is Sony's proprietary "DSD remastering engine" (i.e., DAC) which the Z1 has and the S1 does not. Presumably this means that were one to play the same non-DSD file through both devices the sound quality would be noticeably better through the Z1 than through the S1 assuming otherwise identical systems. At least that's my take on it.