I have had the Sony HAP-Z1ES for a couple weeks. It replaced a very high performance Mac Mini with external PSU. I wanted a change and I am very, very happy with the Sony. One of the goals was to have a "single box" solution: no external drives, cables or power supplies. All of those things are fine and I found the Mac Mini simple and excellent to use with Audirivanna Plus.
There is a lot to like about the Z1 but one shortfall is the onboard drive size being 1TB. Well, it is a 2.5" drive and that has something to do with it. Larger than 1TB 2.5" drives are much less common and larger sizes require a thicker drive than the standard 9.5mm laptop size constraint.
I performed a HDD swap and upgraded to a 2TB from the 1TB OEM. Easy as a few screws and less than 10 minutes. The Player uses a Toshiba MQ01ABD100 drive that has SATA2 with 8MB cache. I purchased a similar drive from Western Digital: 2TB WD Green SATA III Intellipower 8 MB Cache Bulk/OEM Hard Drive WD20NPVX. The WD drive specs out better than the Toshiba (SATA3 vs SATA2) but the Toshiba is available in 2TB as well. I actually have one of the 2TB Toshiba drives in an OWC Elite Pro Mini external enclosure and it is a high-quality, reliable part as well. The 15mm height (drive thickness) will fit in the Sony without modification and a lot of space to spare. The swap was so easy, I put it in the "Pros" category summarized below.
Once the drive is in, turn it on, scroll to the settings section of the menu and select factory default settings. This reformats the drive and copies all of the sample music to it from the onboard firmware. Now you can begin copying files to the doubled capacity. For those with more music and ambition, the Sony HAP-Z1ES seems to be a linux appliance and uses EXT type linux drive partitions. This creates some connectivity considerations and explains a lot of the initially "unfamiliar" limitations for PC/Mac music server aficionados.
Sonic impression: big, big soundstage is immediately apparent and is the most obvious change. It also has a very refined sound with well-defined image and ambient cues. I think the Z1 gives up a little to the modified mac mini in detail but I feel this is due to the black abyss which was the Mac Mini's noise floor (external PSU and onboard filters replaced a switching PSU form Apple). IMO, the Z1 would completely outperform many standard Mac Mini with a good $1000 DAC combos (Price equivalent of the Z1). The DSD processing is very pleasing and the sound in utterly non fatiguing. Rhythm is very good and the sonic signature leans a bit "polite" or "refined". You don't loose the essence of the music within this refinement, just an observation. My Modified Mac Mini was sent though a highly modified Oppo 105.
Back to the linux user benefits. The files transfer method is via ethernet cable and the USB I/O port is for storage expansion. The Z1 can't recognize a windows (FAT, NTFS) or Mac (Journaled, etc) formatted usb drive or thumb drive. It will reformat it before for use, no worry it asks before doing this. Once formatted with the EXT3/4 partition plug it into a Mac or PC and your computer can't read/write it (Unless you use special software - Google it). Linux users s/b able to see the thumb drive and transfer files to it then plug back into the Z1 with no issues. I experimented and this was "hit and miss" using the EXT Mac software (mentioned).
The file transfer can be accomplished directly using a cross-over ethernet cable. It is too slow for my expectations when you are transferring multi-terabytes but does get the job done fairly efficiently. I find this sub-par given thunderbolt technology. This method bypasses the HAP transfer utility program. The HAP transfer utility has some good features but has limited customization options so I opted out of using it. File transfer is easy either way.
Summary - (4.5 stars of 5 possible is my opinion) Pros: excellent sound with up sampling defeat capability (I prefer all of these setting left on), convenient user interface with iOS and Android options, easy HDD capacity upgrade (it almost seemed like they expect users to make this change it was so easy), XLR outputs, simple and useable front GUI, knobs and buttons, very solidly built - it feels like $2K when you pick it up, low mechanical noise, low heat envelope, and a generally intuitive device. For those not comfortable with computer audio, check it out - come to the dark side we have cookies!
Cons: If you remember what this device is and don't get hung up on what it is not, the cons are petty. It's not a DAC, how many CD players have DAC inputs (until recently)? The space inside is available, why not use a 3.5" drive that could reach 5TB capacity? File transfer speed is the only "con" I registered and most folks won't be impacted here. Not using thunderbolt is really a non-starter these days, just do it - it's better, period.
I am going to install Ubuntu Linux on a spare computer and see if that offers some improvements (or options) for files transfer.
The short - I am happy to have it and I would buy it again.
