What constitutes a mid-priced DAC? There’s a ton of room between the least expensive high-performance external USB DAC, such as the $169 HRT MusicStreamer II, and the most expensive, such as an $80,000 dCS combo stack. Almost any DAC that falls between $1000 and $10,000 could be considered “mid-priced” by some audiophile’s standards. So, while the $3200 April Music Eximus DP1 might be on the low side of mid-priced for anyone looking at $10,000 DACs, it’s too pricey for someone on a $2000 DAC budget. But for $3200 the Eximus DP1 delivers a near state-of-the art DAC, robust USB implementation, low-noise multi-input digital preamp, excellent headphone amp, and a stylish looking retro/modern custom enclosure.
Before we dive under its hood, let’s take a moment to admire the Eximus DP1’s enclosure. If its carved aluminum chassis reminds you of designs from Resolution Audio and Constellation Audio, that’s because they were created by the same industrial designer—Alex Rasmussen at Neal Feay Design in Santa Barbara, CA. The DP1’s overall look is modern and clean without being too sterile or self-consciously retro. The figure-eight-shaped volume knob reminds me of my first Nagra field tape recorder, and besides being a nod to the past, the knob’s shape makes it easy to see your current volume level from across the room.
Other niceties that I consider necessities include provisions for simultaneously active balanced XLR and single-ended RCA outputs. I used the balanced outputs for my main amplifiers and the unbalanced for a subwoofer. On the input side, all six of the digital inputs fully support 192/24 format, including USB. The DP1 also has two analog inputs, allowing the unit to function as preamplifier. Analog devotees will appreciate that the DP1’s two analog inputs are pure analog with no A/D and D/A converters anywhere in the signal chain.
The front panel consists of a single on/off switch, a source-selector button with eight options, a source-lock LED, an on/off filter button, an upsample button with three options, a standard ¼" headphone jack, a 1/8" mini stereo input, and the master volume knob. The filter is exclusively for headphone listening; it engages a cross-filter circuit that’s intended to move a headphone soundstage out of your head. The three-way upsample button permits the user to choose no upsampling, upsampling to 96kHz, or upsampling to 192kHz. When you insert a headphone jack into the front headphone connector, the output to the back-panel outputs shuts off. While anyone who wants to use all three outputs simultaneously may find this feature to be a problem, I liked it. I could leave my amp and subwoofer on while listening to headphones. I also liked the single volume control for both headphone and regular listening. Couch potatoes, be forewarned, the DP1 does not include or support a remote control.
Most of the time I had the DP1 positioned so I could reach down with my left hand and adjust any of the controls without moving my head to look at them. It took maybe two days to be able to operate the DP1 “blind.” In my mind that constitutes an ergonomically well-designed audio component.
Under the hood, the signal chain uses the Cirrus Logic CS8416 input chip that can accommodate sampling frequencies up to 192kHz, a low-jitter input receiver, and complete galvanic isolation to reduce external noise from external ground planes. In past reviews of DACs, I’ve seen and heard what a big difference the right USB implementation can make. April Music opted for the XMOS USB solution, which uses a 32-bit XS1-L1 processor and 1Mb of SPI flash memory. The digital signal then goes to a Burr-Brown SRC4192 chip for upsampling and digital conversion. Finally the digital signal is returned to analog via the dual-mono current-output 192kHz/24-bit Burr-Brown PCM1794A chip, which features less than 0.0004%THD and a dynamic range of 132dB. For its power supply the DP1 employs a custom-designed toroidal power transformer, which allows for very low output impedance. Even the circuit board has been physically optimized for low noise and maximum separation between digital and analog components. Finally, the component-output analog-buffer module and headphone-drive module are made up of discrete components rather than an off-the-shelf integrated circuit.
Most of my listening was done at my computer desktop since this product was designed principally for this kind of listening environment. The signal chain was simple: USB from my Mac Pro to the DP1 and then a one-meter length of cable from the DP1 to a power amplifier. For some of my A/B tests I also used the DP1’s S/PDIF and AES/EBU inputs.