The new UHA-4 slimline USB DAC and amplifier combo measures less than 1/2" thick. The first thing you might notice about this amp, besides the slim profile, is the lack of a traditional volume knob. The UHA-4 has a digital potentiometer and an Alps up/down control switch. The digital pot provides channel-to-channel level variation within 0.1 dB - better than most analog pots. Press up or down to increment by one step (2 dB) or press and hold to "scroll". The UHA-4 even remembers the last volume setting it had before powering down, so you don't have to reset the volume every time you turn it on. The UHA-4 also features a simple crossfeed circuit to reduce the unnatural, "inside-your-head" sound which headphones can create. The crossfeed circuit is based on the popular Linkwitz design. The circuit essentially feeds a delayed and filtered version of the sound to the opposite ear, mimicking the way our ears work in a real acoustic environment. When switched off, the crossfeed is in true bypass mode.
The UHA-4 output stage uses the AD8610 op-amp, same as the UHA-6S and UHA-6 amps. This op-amp excels at driving a wide variety of headphone loads.
The UHA-4 is available now for $199. For more information, visit the UHA-4 product page.