The new UHA-6S.MKII is now in full production, and the first units are scheduled to ship in early June. The UHA-6S.MKII replaces the previous model, the UHA-6S, which was discontinued earlier this year.
The UHA-6S.MKII has several improvements over the original version. These include:
- Coaxial S/PDIF digital input. In addition to the optical input, the MKII also has a coaxial digital input.
- Lower output noise. The previous model had two gain settings: +6 dB and +18 dB. It turns out that many listeners need less gain, especially those using in-ears. The two gain settings of the MKII have been adjusted to 0 dB and +18 dB. This moves the usable part of the volume control a little higher on the knob in the low gain setting, and it also lowers the output noise.
- Higher output power. The stock op-amp in the original model was the Analog Devices AD8610 - a great performer and a favorite in the headphone amp community. The MKII will use the OPA209, a relatively new part from Texas Instruments. It was offered as an option for the original model, and it seems to be gaining popularity. Overall I find it's an even better performer than the AD8610. The OPA209 has lower noise, lower current draw for longer battery life, and slightly higher output power capability than the AD8610. Its sound quality is on par with the AD8610, and many even find the OPA209 preferable. For those who want to match the sound of the original model, the AD8610 will still be offered as an option.
- New case design. The MKII case design is thinner and rounded on the sides, giving it a streamlined look. The MKII case is similar in overall footprint area to the UHA-4, just slightly thicker (0.8" or 20 mm).
Like the original model, the UHA-6S.MKII is compatible with the iPad when using the camera connection kit.