I was the first one on the iOne iTour, so without any further ado, let's have at it:
1. iOne = iFun. I can stop writing (and you can stop reading) now and be done with it.
2. Size: about the size of a credit card and maybe about 10 credit cards thick. The iOne can fit in a pocket and go ANYWHERE you go with no hassle whatsoever.
3. Features:
a) Three inputs: USB, S/PDIF, and Bluetooth (BT from here on out)
b) S/PDIF can be used as an input/output (with one limitation – see below)
c) RCA outs: similar to most all iFi gear
d) iFi logo is color-coded: it tells whether there is signal lock, and various colors provide the signal throughput (16/44 → DSD256)
e) Supplied:
1. Power adapter to provide USB power (when USB not used for signal transmission)
2. USB cable (approx. 1' long)
3. RCA cables (again, approx. 1' long)
4. Limitations:
a) No volume control. This must be intended for use in a hifi rig with traditional volume control (via integrated amp) or with BT control of the volume. When I listened on my Desktop system (via JRiver) and changed albums, I needed to get up to change the volume on my active JBL's. Wasn't a total dealbreaker, but I bet this might get a little annoying if you were listening to a larger collection of tunes on random play mode. Honestly, I wish this had a volume control, but it's hard to imagine how/where they'd fit it in such a small footprint.
b) No internal battery. Not the worst thing in the world because that's how the design is so small and light. However, this means you need to have USB power engaged at all times.
c) Energy efficiency: I was able to power the iOne via a portable phone charger for over two days during testing with plenty of charge left over. The iOne is a “power sipper” and must be pretty energy efficient.
d) S/PDIF defaults to audio out when USB is engaged. This is a neat design feature, but it presents one problem: unless you have a longer USB cable than the supplied one, you may be limited in your hi-fi rig as to where you can place the iOne.
e) Two filter choices, not as many as other iFi products. Not a big deal for me because I tend to dial in what I want with iFi gear and never touch it again.
5. Sound:
a) Burn-In: I didn't notice any huge burn-in effects. Period.
b) Tonality: the iOne presents is brighter than my iDSD (with iUSB power); iDSD has a fuller, meatier sound, maybe even slightly darker in some cases. So the iOne is brighter and more 'lit up', but not harsh in any way.
c) Resolution: pretty good. It's not as resolved/detailed as some of the pricier iFi gear.....but would you expect it to be?
d) Soundstage: not as deep as the iDSD. A somewhat shallower/flatter presentation, but mainly in comparison with the iDSD. It's not something that stood out to me as lacking when just listening solely to the iOne.
e) BT: no sir, I don't like it. It's not the iOne's fault, it's just not a good protocol (IMO). It seems like BT was designed with the masses in mind, less so far the (small) minority that require great sound. Convenient? Yes. Sounds good? Not as good as USB or S/PDIF – if you're an audiophile, stick with them. I know that folks may disagree with this, but that's my opinion and I'm sticking to it.

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f) In the main rig: the iOne doesn't give up tons to pricier DACs. DAC technology has really improved in the last 5 years. There is a slight veiling of highs and (of course) the control of the low end is not as precise. I attribute those two to going off the (typically noisy) USB power of a Mac/PC. Otherwise, it sounds mighty nice....especially for the money. Yes, you can tell the difference between the iOne and a more expensive DAC, but I think that misses the point given the iOne's market positioning.
g) Value for $$$: with most bargain DACs, I can hear right away why they are less costly. Their faults are obvious, and the differences between them and more expensive DACs are even more so. For the iOne, there is slightly less resolution and soundstage, but whenever I found myself noting these, my immediate thought was that I was being too picky. I haven't heard the Audioquest dongles, but this is the first under $200 DAC that I actually like. Well, I amend that (somewhat). I think the original AudioSector NOS DAC (without chassis) was around $200, and that was pretty darn good......but I think that was over $200, not under. And the AudioSector Dac was solely S/PDIF, not portable, and handled 16/44.1 files only.
6. Fun Quotient: off-the-charts. While breaking this in I listened to Manuel Göttsching “E2-E4,” an early electronica classic, during my lunch break. Sound was poppin' from the JBL's and I found myself bouncing in my seat. My 9-year old daughter was able to play YouTube tracks from her iPad (via BT) at a whim – she even asked if she could try the iOne out on *her* system....which she never does. I'm guessing the iOne, especially the BT, is designed primarily for the newest generation of listeners, and it succeeds mightily on that count. iOne brings the iFun. For a beginner system (laptop and/or BT into powered speakers), this is 'da Bomb....just gotta figure out the right volume control solution. I might get one of these for my daughter, and I would certainly recommend this to any kids going to college and/or just graduating as a 'gateway drug' into Audiophilia.
-dB (with gear envy - again.....curse you, iFi)
Equipment Used:
1. Base system: MacBook Pro (running JRiver) → iFi iUSB → iFi iDSD → JBL LSR305 monitors
2. Comparison #1 (Desktop): MacBook Pro (running JRiver) → iFi iOne (USB input) → JBL LSR305 monitors
3. Comparison #2 (Main Rig): Mac Mini (running JRiver) → AR-T Legato USB-S/PDIF → iFi iOne (S/PDIF input) → Tortuga Audio LDR volume control → Channel Islands D100 Mk. I → Horning Perikles Ultimate speakers (96dB, 8 ohms)
4. Comparison #3 (BT → Desktop): iPad/YouTube or Macbook Pro/JRiver → iFi iOne → JBL LSR305 monitors
Music Used:
1. Glen Campbell “Wichita Lineman” (1968 – 2008 Remix)
2. Tara Jane O'Neil “Blow” (2017)
3. Slowdive “Star Roving,” “Sugar for the Pill” (2017)
4. Chano Domínguez & Niño Josele “Django” (2014)
5. Lila Downs “Palabras De Mujer” (2017)
6. The Regrettes “I Don't Like You” (2017)
7. Ryuichi Sakamoto “Plankton - Music For An Installation By Christian Sardet And Shiro Takatani” (2016)
8. Holly Macve “The Corner of My Mind” (2017)
9. Edu Lobo “Casa Forte,” “Jangada” (1971)
10. Bobby Lee Trammell “Shirley Lee” (1957) – from a *STELLAR* compilation CD “James Burton: The Early Years 1957-1969”
11. Harry Bertoia “Sonambient Collection” (2017)