Design and Under the hood.
While today’s DAPs are getting bigger and bulkier, DTR1 is very compact at 100 x 56 x 16.4 (mm) which is a little taller than a deck of playing cards. It fits comfortably in a palm of my hand, not too heavy (only 146g), and easy to operate with a thumb across its control buttons. This is a very minimalistic non-touch screen design with a small 2.5” display and 5 navigation buttons below it (4 directional and middle for select, play, and pause). On the right side you’ll find Volume up/down (60 steps), a power button underneath, and a spring-loaded micro-SD card slot below it.
The bottom of the DAP has Line Out, micro-HDMI charging port, hardware Reset pinhole, and 3.5mm TRS headphone output. The chassis are precision machined using aviation grade, lightweight aluminum alloy, back panel appears to be glass, and internally DTR1 is shielded to avoid EMI interference. I have been using it so far without a case, and surprisingly it feels secure in my hand. But that’s probably due to its small size which allows me to hold it with a better grip. There is an optional case for it which I’m waiting to receive soon.
Under the hood, the design is based around a single AKM AK4490 DAC, not exactly the latest offering. But regardless of that, I decided to treat DTR1 as a black box (literally) and to judge it by its sound rather than its DAC and other components. In addition to AK4490, Anson also picked a popular TI OPA1611 SoundPlus high performance op-amps used as low pass filter (LPF), and Analog Devices AD8397 high output current op-amp to drive the headphone amplifier output.
That high-current op-amp is the key here in how well DTR1 pair ups with some of the more demanding headphones. You get a powerful output of 6.4V in high gain, which translates into approximately 136mW of power into 300ohm load, and over a watt of power into 32ohm load, though it will be an overkill for lower impedance IEMs and headphones. Thus, going to low gain (about 1.7V output) when using IEMs should be enough. Either way, you get low, mid, and high gain setting.
Another important part of the design is using a dual high-density battery power system and making sure there is no noise coupling between digital and analog parts of the circuit. And as I already mentioned while talking about the charger, DTR1 uses +/- 8.5V power supply unit which improves efficiency and ensures a direct power path without up-converting from a lower battery voltage like in majority of other DAPs with 5V USB charging interface and 3.6V li-po batteries. And the battery should last over 10hrs on a single charge.
While it’s not the latest AKM DAC, though it used to be flagship not too long ago, it’s still very capable and will support plenty of lossy and lossless formats, such as wav, flac, wma, mp3 and aac, alac, aiff, dff/dsf, ogg with sample rates up to 192kHz and DSD64 (as tested and confirmed). And especially when dealing with large size high-res files, it’s good to know DTR1 can read up to 512GB card and supports 150k song limit.
If you are coming off a typical Android based DAP with a touch screen GUI, DTR1 will take you back 4-5 years due to its very minimalistic interface and a physical click button navigation. But it’s all part of its deeply-customized Linux OS and the need to use physical buttons to move around. The good news, you can figure out navigation within seconds, there is no learning curve. The bad news, you will have to do a number of clicking while navigating around or going through the list of your songs, though you can scroll one track at a time with a single click or hold up/down arrows to go faster by scrolling a screen/page at a time.
Once powered up, you are in the Main screen which has navigation options at the bottom for Current file, All Songs, My Favorite, Folder Browsing, and Settings. At the top, Notification bar has indicators when micro SD plugged in, volume level, play/pause indicator, gain setting (low, mid, high), play mode, and volume level (bar indicator).
The actual Playback screen has info about the song such as bit depth and sampling rate, title, playback progress bar, and embedded artwork if one available. Up/Down arrows skip songs, Left/Right long press arrows fast forward/back through the track, and left arrow takes you back to the previous screen. While in Playback screen, long pressing middle button brings up Play setting pop-up menu where you can tag the song as Favorite, delete the song, change Play Mode (loop all, loop one, random), select to play CUE file, change the gain setting, and change the filter setting.
System Setting menu has System info, Language, Play Mode, Backlight, Brightness, Wake up mode (any key or power key), CUE playback enable, Gain selection (low, mid, high), Filter selection associated with AK4490 digital filters (sharp roll-off, slow roll-off, short delay sharp roll-off, short delay slow roll-off), auto shutdown, database update (to scan micro SD card), and Reset of all settings.
As one can see, it’s not just a minimalistic interface, but also a limited set of features for now, though it’s still a work in progress. Anson listens to user feedback and reflects it in his firmware updates. But I have a feeling, he wants to keep this audio playback OS lean and optimized, so it’s down to bare minimum when it comes to features. The focus is the sound quality which I’m going to discuss next.