• The DACport headphone amp uses a direct coupled (capacitor free) class A amplifier circuit said to maintain “audiophile quality all the way to the headphones.”
• Output power: 1.5 watts, said to be capable of driving even 600-Ohm headphones.
• Output impedance: 10 Ohms (which may cause interactions with some headphones that explain the sometimes slightly light bass balance we observed in some cases).
• Noise: The DACport is extremely quiet. Its noise floor tracks close to -130dB across most of the audio spectrum, gradually rising in the region from about 300Hz on down toe 20Hz, where noise climbs to approximately -112 dB—still a very low figure.
• 18V power supply: The DACport amplifier is fed by what CEntrance describes as “super-clean 18V rails (±9V, bipolar supply).”
About the DACport power supply:
CEntrance’s chief product architect Michael Goodman kept a development blog as the DACport was under design, and in the blog excerpts below he explains the unit’s distinctive USB-fed power supply in some detail.”
“…when you first plug it in, DACport starts in ‘low power’ mode and takes only about 60 mA of current on the 5V supply. In this startup mode it performs initial USB handshaking and then requests additional power…”
“Having performed initial USB handshaking, DACport requests full power, which is granted by the OS. That starts up the main switch-mode power supply that ramps up the 5V to +/-9V for the audio circuitry, +3.3V for the digital circuitry and clean +5V for the converter circuitry. In total, DACport has 5 (five) separate internal power supplies! That’s how we ensure that clean power is supplied to all circuitry to maintain the ultra-low distortion.”
“When designing the DACport we took a close look at the amount of power available from the USB jack. Typically it’s 5V x 500 mA, which results in 2.5 Watts of power. Not all of it is available for Audio however – in fact about 1 W is taken up by the digital and converter circuitry, so 1.5 Watts is the real Audio output power. In most cases, that’s plenty, since even the low-impedance headphones are very loud at 500 mW. DACport makes 1.5W available for audio.”
• The DACport is housed in a handsomely finished tube-like extruded aluminum enclosure fitted with a flat-plate end cap on the input side (the plate provides a USB jack and power-on status light) and with a semi-conical metal plug on the output side that holds the ¼-inch output jack. Completing the pictures is a side-mounted soft-rubber volume control knob.
• The DACport is shaped (and roughly sized) like a high-tech, machine age, aluminum “cigar.” It is extremely compact, weighs just 72 grams, and would fit easily in a pocket, handbag, or computer case.
• Accessories include a low-EMI USB cable, a belt clip, and a felt carrying pouch.
During my tests I used the DACport in its primary intended capacity; namely, as a combination DAC/headphone amp. For this reason, my comments on the DAC and amp sections of the DACport are, of course, intrinsically linked. Early on, I found that the DACport, like many other class A amplification devices, needs to be fully warmed up to sound its best. My comments, then, refer to a unit that has warmed up for between 15 – 30 minutes, or even more.
First off, let me say that the DACport is highly detailed and offers plenty of resolving power—more than do many of the standalone DACs that I’ve heard at or even well above its price point. If you enjoy components that can dig deep into digital recordings to extract very fine, low-level content and transient and/or textural details, the DACport will not disappoint. Also note—again, once fully warmed up—that the DACport exhibits virtually none of the upper midrange/treble shrillness or edginess you might encounter with some USB DACs. On the contrary, the DACport sounds as if it is ready, willing, and able to go toe-to-toe in competition with DACs that offer coaxial or TOSLINK S/PDIF interfaces. This, I suspect, is a quality attributable to CEntrance’s sophisticated USB interface and clock management technologies.
Upper mids and highs are very clean and clear sounding, and they exhibit a remarkable ability to resolve subtle echoes, reverb tails, or the leading edges of transient sounds (which can, for some DACs/amps, be very hard to get right). Upper mids and highs are also generally smooth, though warm-up certainly helps in this regard. You might find, however, that the upper end of the DACport’s response range sounds just a smidgeon brighter than the equivalent ranges as played through DACs/amps with tube output stages.