https://ifi-audio.com/portfolio-view/x-xdsd/ I didn't see an existing thread, so I figured I'd start one. Full disclosure: This product was loaned to me by @jexby as part of the SBAF loaner tour. He paid me a lot of money, gave me booze, and provided prostitutes in exchange for me to shill this product my honest and unbiased opinions about the x-DSD. Names have been changed to protect the innocent. Suspects are presumed innocent until proven guilty in a court of law. Do not take x-DSD if you are allergic to it or any of it's ingredients. Side effects may include nausea, diarrhea, or death. * With that out of the way, here is my completely honest (yet unfair) review of the iFi x-DSD.** I'm reviewing the x-DSD in the following configurations: HP Z440 workstation -> USB -> x-DSD -> TRRS to 4 pin XLR adapter -> ZMF Eikon. x-DSD set to "Listen" filter. 3D+ and XBass+ disabled. Google Pixel 2 XL -> Bluetooth -> x-DSD -> TRRS to 4 pin XLR adapter -> ZMF Eikon. x-DSD set to "Listen" filter. 3D+ and XBass+ disabled. ERGONOMICS: Pros - It's much smaller than I imagined it would be, as it is roughly the size of a deck of cards. The volume dial is easily accessible. It feels sturdy. Cons - The black plastic volume dial doesn't seem to be recessed quite enough to protect it from stray pocket rotations or clicks. (The volume dial also serves as the power button.) The volume dial doesn't have a lot of resistance to it. It does have "clicky" rotation stops, which means that as you turn it it clicks into the next volume setting. (I hope that made sense.) Unfortunately, it doesn't click firmly into each of these locations, and feels kind of vague. The volume / power button setup just kind of feels cheap to me in an otherwise nicely built portable device. In fact, I would call it the single worst feature of this device from a design point of view. Blue USB data cable seems to have a proprietary sized end on the unit's side. It's more like an extension cable than a typical USB A to B cable. Not sure if finding replacements or spares would be easy. @jexby either forgot to send the USB micro-B cable (the charging cable) along with the unit, or it didn't come with one. I have plenty laying around, and tried a few. They all seemed to loosely fit into the connection, which doesn't inspire confidence. Pairing Bluetooth was a PITA the first time. The pairing instructions on the card go something like this: "Press and hold." Literally, that's all it says. Thanks? It took several attempts to figure out when to release the button, what to look for to indicate a pairing mode, and even then it wouldn't pair the first few times with my phone. Mehs - The USB signal cable won't charge the device. You have to use the separate micro-B connection to provide the 5V for charging. 2 doses of USB in one tiny device. (Yay?) The multi-color LED that serves as a volume indicator and on/off light is vague. I couldn't quite remember what color they said match to what volume setting, and I don't care to try anymore. Basically, it's a less fancy Chord Mojo color ball type indicator. I guess I'm picking nits, as it's better than nothing. SOUND: I am fully aware that I'm testing this tiny, battery powered, portable device with a full sized 300ohm closed dynamic headphone. That is why I said this review was unfair. It doesn't sound bad! It doesn't sound good, either. It vaguely reminds me of my old iDSD BL. The xDSD can drive the Eikons to pretty darn loud volumes - enough that you wouldn't want the headphones over your ears at max. Despite this, the quality of the sound suffered greatly trying to push the Eikons. The tone didn't sound completely neutral to me, but it wasn't unpleasant. Bass seems to have an emphasis to it, while upper mids seem to have a little bit of a recess. As far as dynamics, staging, and all the rest of it goes - it's really struggling to drive these Eikons. Bass isn't well defined and is very fuzzy, although it provides plenty of bass volume. The highs seem hazy, and imaging and detail isn't being rendered well. Plankton? Only if you drown this thing in the sea. 3D+ was way more subtle than I remember the iDSD BL being. Perhaps iFi has learned - less is more? Either way, it didn't do the sound any favors on the Eikons, so I stopped using it. Staging was still pretty narrow, the timbre of the treble changed subtly, and the music just sounds better with it off. Oh well. XBass+ was also more subtle than I recall on other iFi devices. I'm good with that. It could also be that the xDSD just can't feed the Eikons what it needs to make these features sound good. Compared to my normal desk setup, it just can't keep up. (Duh.) I'd say this is to be expected with high impedance headphones and micro-portable devices though. I imagine it would perform very well with a good pair of IEMs. So, we learned the obvious in this exercise. IEM portable dac/amps shouldn't be used to drive full sized high impedance headphones, even if said headphones are fairly efficient. In short - everything I said above was 100% honest*** yet completely unfair. ----------------------------- ** I don't know where my IEMs went. I asked to borrow a friend's CA Orions (which I quite like and am familiar with how they sound), but that arrangement fell through... so... when life hands you lemons, write snarky reviews. =/ *** Except the part where I said Jexby gave me cash and prostitutes. He didn't give me either, the stingy bastard.