Acoustic assessment of DT-1 was done in two phases. At first, the single-ended headphone output was used to drive our Grado RS-2, to evaluate the operation of the device functioning as a headphone amplifier. Then, the Line output was used to evaluate the DAC section. In both cases, we used the device through its coaxial S/PDIF input, using an Innuos Zen Mini Mk3 as a source. As a Line level source, DT-1 was connected to the usual reference system, which includes the Melos Plus Series Line preamplifier, the Parasound HCA3500 power amp, and the ATC SCM-50PSL loudspeakers.
Installation of the device did not show any difficulties, but the user just have to leave enough space above the tubes for obvious reasons (however, the relevant temperatures are not excessive, anyway). Although we did not use DT-1 extensively as a USB DAC, however, both driver installation and use with the foobar2000 media player in ASIO mode were straightforward. This also applies to Bluetooth wireless streaming. Connecting a compatible source was easy and the connection was very stable, without dropouts. If you have a device that supports aptX HD, quality is very good and this connection is a first-class alternative for ad-hoc listening to a music collection or online stream that is not available through the home network.
First impressions you get while listening to DT-1 through headphones, include one of an amplifier that has a good driving capacity, a pleasant and relaxed sound character, with good extension and feeling of air at the high-frequency band and offers low noise level, which can sometimes come to be perceivable, but not annoying. Since we know, from the relevant measurements, that a significant part of the noise is associated with the tubes, this is most likely to improve by changing these components to something better (the user manual has a proposed list, by the way). Nevertheless, if absolute silence is important, the user can bypass the tube-based buffer stage, an option that, in addition to silence, also offers a somewhat better very low-frequency extension, better-bodied instruments in the region, and a better sense of vibrancy. Stereo imaging was very good and listening to binaural recordings creates an excellent illusion of focus and movement description for the sound sources included in the mix.

Using the DT-1 as a DAC, through its line output, the first impression was that of a disciplined, well-controlled device. The system sounded pleasant, somewhat on the soft-rounded side, but never overstating this character, offering a very good soundstage and macrodynamics.
With the tube stage inline, the system offered good low-frequency extension with a good presence, volume and pulse descriptions, and satisfactory (but perhaps too much) control. The rhythm section appeared with good fullness and speed characteristics and with a proper, pleasant sense of flow. Acoustic instruments rich in low-frequency information were properly described, sounded somewhat hazy and airy, but without depriving the listener of any decisive detail.
Mid-band, DT-1 is quite ear-friendly and relaxing, offering the right level of presence, and being a little laid-back. This behavior creates a feeling of realism and naturalness in the listening room and the listener never gets tired. The overall result is pleasant, with good dynamic headroom and no sense of compression.
This feeling of realism is intensified by the good stereo imaging the device offers, a behavior that can be attributed, partly, to good channel balance and low crosstalk, mentioned in the lab session. The focus of individual audio objects, the feeling of air between instruments, and the sense of stage depth were at levels disproportionately good relative to the device's price tag, the sound stage being clearly one of its very strengths. The reference system, with the DT-1 as a DAC was impressive when the music track so mandated, with some serious performance capacity, somewhat rough and fuzzy compared to the result I am accustomed to using the reference DAC (Teac Esoteric D-70), but that is something you expect, of course.
Towards the top part of the audio spectrum, performance was also good, with a good sense of extension, good timing attributes both in the attack and the damping part of percussive details, slightly diverging towards the thin-bodied. Balance seems to deviate a little bit to the soft and mild, but without any excessive behavior that ends up in creating a euphonic fingerprint, as it is obvious that a middle ground was found here. Harmonics were properly rendered and the overall listening was bright and pleasant, with a moderate feeling of warmth.
Finally, one of DT-1's most successful aspects proved to be the differentiation of its performance when choosing the "Tubes off" mode. Clearly, there were differences in some critical points, but we are not talking about whopping changes, rather subtle variations, both audible and useful, the only point of actual criticism, here, being a small but perceptible change in signal attenuation which can be confusing, at least initially.
Without the tube stage on the signal path, the final result picks up a bit in volume and presence in the very low-frequency band (something that is confirmed by the frequency response), resulting in successfully highlighting the low bass part, without becoming heavy and excessive. The final result sounds a little more descriptive with better articulation in the middle band and generally creates the impression that it is more accurate, offering better detail and, maybe, being a little more dynamic and fast. The balance between the two operating modes, however, is carefully made with both of them equally useful, offering a tool rather to adapt in the temporary program and listening circumstances than to ultimately decide between a tube-based or a solid-state architecture. This is a game that will always keep the listener's interest and will give another dimension to listening to his music.

Conclusion

In conclusion, it is impossible to think about something you are entitled to, to this price tag, that DT-1 does not offer. It includes all the necessary connectivity, a means to tailor its sound to your preferences, and to experience tube-based audio, it is a good introduction to high-quality reproduction through headphones and explores the idea of audio streaming.
This is a reasonably priced device, designed and manufactured with the minimum possible compromises. Highly recommended!

Listening Sessions Recording

The following recordings were made with a DV-RA1000 Tascam master recorder (using 24bit/192kHz sample rate) and you can download them to have an impression of what the device under review sounded like. It is obvious that any recording of this kind could not be absolutely transparent but, according to our experience, the majority of sound attributes we listen to, during the actual listening sessions, are preserved. No need to say that you should use these samples cautiously and for informative purposes only. Do not rely on them exclusively to make any buying decisions. The file format is .flac, so expect that the zipped files will be quite large (even if the clips are about a minute or less long. You could use an ABX listening tool like the ABX plug-in for foobar2000 if you want to make some more elaborate experiments. Contact us if you have any questions.

Listening Sessions Recording TOC
Track #01-04	Aoshida Dilvpoetry DAC DT-1, S/PDIF Coaxial, 16-bit/44,1kHz.
Track #05-06	Aoshida Dilvpoetry DAC DT-1, S/PDIF Coaxial, 24-bit/96kHz.
Track #07	Aoshida Dilvpoetry DAC DT-1, S/PDIF Coaxial, 16-bit/44,1kHz, Tubes Off.
Reference	Αναφορά: Teac Esoteric D70 | dCS Puccini U-Clock.

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