While it seems like desktop and home audio systems have only the smallest gains left to make in terms of increasing the sound quality and performance to the maximum level physically possible, portable audio still has some work to do to match up to bigger systems in a smaller package. While the ultra-portable space has seen an explosion of high quality options, the next generation of larger “transportable” DACs and Amps is also gaining ground, with products becoming more and more competitive with desktop gear. Does the iBasso D17 Atheris elevate this class even further than iBasso’s previous offerings?

Build and Design

D17 is a transportable DAC/Amp combo that combines Tube, R2R, and 1-bit technology. While the tech inside is cutting edge, the general look and design has a more rugged, vintage style. The exterior is aluminum with a few controls and a monochrome OLED screen. For inputs and outputs, you get two USB-C connectors in the back, one for power and one for digital audio input, along with a mini digital coax connector. The analog outputs on the front 3.5mm and 4.4mm can be used for either headphones or line out connection to another amp.

The main controls for the device are the two knobs in the front. One is a 24 step fully analog attenuator, and the other is a digital volume control. The digital volume control is also a button which enables you to access the menu and manage the device settings. The D17 package includes a USB-C to USB-A charge cable, USB-C to Lightning and USB-C to USB-C OTG data cable, a mini coax cable, and an analog interconnect.

The internal components and design of D17 is quite impressive, with the two isolated DACs, iBasso’s FPGA-Master 3.0 tech, and femtosecond oscillators. To help reduce noise from the tubes, the device is internally shielded from vibration and engineered to isolate the tubes from potential internal sources of ringing or vibration.

Features 

D17 has three modes for audio processing:

1. In NOS mode, PCM audio is decoded via the R2R DAC and DSD audio through the 1-bit DAC.

2. In OS mode, DSD audio is converted to PCM and all audio is processed by the R2R DAC.

3. In SD mode, all audio is converted to DSD and processed via the 1-bit DAC

This gives you some freedom to test the sonic character of the 1-bit vs R2R DAC, while still providing the option to limit any changes to the audio stream, and process the digital audio in its native format.

The amplifier uses Korg Nutube 6P1 tubes coupled with a solid state buffer amplifier for what’s technically a hybrid tube/solid state design. The amplifier can run in either headphone or line mode, enabling you to use D17 as a standalone device or with an external amplifier. In addition, D17 features High or Low gain mode selection for both the DAC and Amp stage, and L/R balance controls.

The dual volume knob configuration lets you take advantage of the 24-step attenuator while also getting the advantage of more fine tuning. My process for finding the best volume was to first max out the digital volume, then set the analog volume a couple ticks above my preferred listening level, and finally reduce the volume with the digital control to fine tune it.

D17 uses a dual battery design to help further isolate the final signal output, but there’s no direct indicator of each battery’s life like other iBasso devices. In total the expected battery life is 15 hours of playback, but that’s assuming low gain and moderate volume levels, so using it to drive over-ear headphones at high gain will result in lower battery life.

Sound and Performance

D17 builds on iBasso’s previous transportable devices, taking aspects of the D16 Taipan PB5 Osprey and combining them with some new ideas for something fresh. The simplicity also proves to be a real standout here, eschewing designs with 10 different buttons and switches, for two knobs, two buttons, and three modes that can help transform the sound.

The R2R mode is your classic warm, “analog” sound that gives a more relaxed presentation without losing the dynamics or the upper air and extension. While there’s a bit of color to the sound, there’s a very natural character to the instruments and voices, and it doesn’t lack for spaciousness or separation either.

The 1-bit DAC offers a more incisive, detailed sound that reveals more of the smaller intricacies of the music, but never gets too bright or fatiguing thanks to the tube amplifier stage that takes just enough edge off the sound to maintain strong musicality in spite of more revealing aspects of the digital processing.

In terms of power, D17 handles both ends of the spectrum very well:  from sensitive IEMs, to hard to drive headphones, everything felt well managed. Noise-prone IEMs had no hiss in low gain, and the digital/analog volume control could also be used to tweak things a little and really deliver a pitch-black noise floor. For over-ear headphones, D17 was a step above the average portable, giving heavyweights like the Dan Clark Audio E3 and HIFIMAN HE1000 Unveiled really strong performance.

Comparison: iBasso D16 Taipan, iFi Valkyrie

So now we have to ask, exactly how much does D17 improve on its predecessor? And how does it stack up to the other big DAC/Amp combo released this year: iFi Valkyrie? While D16 is a pretty straightforward comparison, Valkyrie is in many ways a completely different kind of beast than D17.

Compared to D16, D17 is a clear, all-around upgrade. D17 provides – in any mode – more detail, a bigger soundstage, and a stronger performance with a wider range of headphones. Switching back and forth between the two, it felt like everything was just turned up one more notch: the detail and insight, the dynamics, and even the emotional quality of the sound. Along with that, the stronger performance with over-ear headphones make D17 a clear win.

Valkyrie’s larger feature set and higher power output offer a bigger challenge. Valkyrie does have the edge with the hardest to drive segment of headphones, providing a bit more body and dynamic feeling with those upper tier planar magnetics, and it has a lot more sound customization options, like XBass and XSpace. Where D17 is stronger is the raw detail it delivers and its overall more natural presentation. I don’t think there’s a single setting on Valkyrie that is at once as natural, detailed, and dynamic as D17’s 1-bit DAC mode, and the R2R mode adds some of the euphonic musicality that XBass can, while remaining more natural sounding. That said, it can’t match up with the sheer fun of XBass’s low end extension, and I think with some of the oversampling options, Valkyrie might be able to squeeze a hair more detail from the sound – though at the cost of timbre.

Final Thoughts

Sometimes it feels like HiFi audio exists in a perpetual chain of 2 channel speaker systems trying to sound as much like live music as possible, desktop headphone systems trying to sound as much like speakers as possible, and portable systems trying to sound like desktop systems. With D17 Atheris, have portable systems managed to “catch up” and sound as good as desktop systems? Honestly, it’s really close, and while there might be better desktop DACs and amps available for $2000, D17’s combination of features, sound quality, and performance comes as close to closing the gap as ever.

https://bloomaudio.com/products/ibasso-d17