NuForce is a brand that will by now be familiar to many Playback readers because we have used their excellent Icon Mobile portable headphone amp as a value-priced reference for several years. NuForce has recently released a headphone amp with a built in DAC for desktop use, called the Icon HDP, which is the subject of this review.
NuForce claims that the HDP’s analog headphone circuit has a high current design with a simple circuit. The analog section is separated from the digital section on a different circuit board and features its own separate, isolated power supply regulator.
The digital section uses four 24/192kHz DACs that provide a fully differential and balanced output to avoid the need for coupling capacitors. While the USB input is limited to 24-bit, 96 kHz inputs as is normal, the coaxial input, consistent with the DAC design, can handle 24-bit, 192 kHz data streams.
For this test, we used the Sennheiser HD 800s, HD 650s, the Denon AHD-5000s and the Beyerdynamic DT 990 headphones as our listening references. We also compared the DAC section of the Icon HDP to the DAC section of our reference Esoteric DV-60 universal player.