Alpha Design Labs (ADL) X1 24/192 USB DAC Headphone Amplifier
bile operation. It supports a direct digital connection for all-butthe-oldest iOS devices via an Apple MFI certified USB cable connection for playback of up to 16-bit/48 kHz music. High-resolution file playback is also supported, up to 24-bit/192kHz, by USB cable connection to a PC or Mac computer. I should mention that the ADL X1 does not have the ability to digitally connect to Android devices. However, ADL has this covered with the ADL A1 model ($649) which also offers DSD 2x decoding (2.8M and 5.6M) when connected to a PC or Mac.
The ADL X1 is about the size of an iPhone with about twice the thickness. It measures just 6.8 cm (W) x 11.8 cm (L) x 1.65 cm (D) and weighs a mere 147g. The sides and back of the X1 are made of an ABS plastic, however, it is in a tasteful matte-black with a suede-like antislip feel. The face is brushed aluminum and hosts six miniature white LED lights which indicate the incoming music signal sample rate – a great feature in my book. The faceplate is offered in four anodized metallic finishes, including: blue, black, silver and red. The review sample came in the red, which I really liked – though I confess that I’m a bit of an attention seeker when it comes to my mobile gear. Overall fit and finish is very good and if I had to pick at anything, it would be the volume control, which is made of a seemingly inexpensive plastic with a position notch that I found difficult to see. To its credit, the volume knob did have a positive on/off click and felt snug across its sweep.
The ADL X1 sports numerous connec- tions, including an analog 3.5mm headphone jack and 3.5 mm line-in jack, and a slider-switch marked as 1/2 GND TRRS that allows for matching to different 4-pin headphone types (Sony or Apple). There is also a USB miniB socket for computer/ charger connection, a USB A Apple MFI Certified socket for Apple devices and a 3.5 mm headphone out jack that doubles as a mini-optical S/PDIF 24/192 digital output. A slider-switch can be found on the back-side to toggle between Apple/ computer connection.
Internally the X1 uses some fine parts, including: a high-performance ESSES9023 24-bit/192kHz DAC chip, a 3.7V 2600mAh lithium-ion rechargeable battery (7.5 playback hours) and a 4-layer gold-plated printed circuit board. The X1 can be recharged via a computer USB connection or a dedicated power supply (sold separately). Maximum power output of the X1 is 34mW (12 ohm), 60mW (16 ohm), 82mW (32 ohm), 86mW (56 ohm), 36mW (300 ohm) and 19mW (600 ohm) – all at 1% THD/1kHz. Please see the “quick info” box at the end of this article for total harmonic distortion and signal-to-noise ratio ratings.
The ADL X1 came packaged well in a slip cover box with a foam insert. Along with the X1 itself, the box contained a generic USB cable (Type A to mini-B), a 3.5mm to 3.5mm cable, USB-A to 30pin MFI iDevice cable and dust plugs for the USB and optical S/PDIF jacks. And, I can’t forget the handy ADL-emblazed silicon elastic band for coupling the X1 to a music-player/smart-phone.
To evaluate the X1, I used it with my 3rd generation iPad using the included USB-A to 30pin MFI cable as well as an upgraded ADL iD-30p cord ($66). To test high-resolution file playback, I connected the X1 to my PC using the included USB A-miniB cord, as well as, an upgraded 1.8 meter ADL Formula 2 USB A-miniB cord ($66). To make this work, I had to install a software driver for the X1 from the ADL website. Though I do own an