OPPO HA-2 Portable Headphone Amplifier/DAC OPPO HA-2 User Manual Spoiler: Specifications Designs and specifications are subject to change without notice. General Dimensions (W x H x D)2.5 x 6.2 x 0.5 inches, 68 x 157 x 12 mm Weight6.2 oz, 175 grams Frequency Response20 Hz - 200 kHz Audio-in Level1 Vrms Line-out Level1 Vrms @ 0 dBFS Recommended Headphone Impedance16 Ohm - 300 Ohm Maximum Headphone Output Power300 mW into 16 Ohm 220 mW into 32 Ohm 30 mW into 300 Ohm Output Jacks3.5 mm stereo headphone 3.5 mm stereo line-out Input PortsAnalog: 3.5 mm stereo audio-in Digital: USB A for iPod / iPhone / iPad; USB micro-B for smartphones with USB OTG feature and computers. DAC ChipESS Sabre32 Reference ES9018-K2M Input FormatStereo PCM, Stereo DSD (DoP v1.1 or native) PCM Sampling Frequencies44.1 kHz - 384 kHz, 16 / 24 / 32-bit DSD Sampling Frequencies2.8224 MHz (DSD64), 5.6448 MHz (DSD128), 11.2896 MHz (DSD256, native mode only) ProfileUSB 2.0, USB Audio 2.0 Battery Built-in Battery type3000 mAh lithium polymer rechargeable battery Battery Operation TimeApprox. 13 hours for analog source via Audio-in; approx. 7 hours for digital sources via USB Charging TimeApprox. 1 hour 30 minutes Spoiler: Bass Boost Frequency Plots Normal: No bass boost applied. The frequency response is flat. Bass Boost: Bass boost is turned on. Low frequency band gets a boost. Bass Boost Detail: Bass frequency below 100 Hz gets about 5dB boost. The boost gradually decreases from 100Hz to about 500Hz where it reaches the normal non-boosted level. Now that the HA-2 has been officially launched as of this afternoon (February 20th, 2015) I thought it would be appropriate to start a new discussions thread that was originally started in the Sponsors Forum when we revealed the HA-2 and the PM-3 to the public for the first time at the Rocky Mountain Audio Festival in 2014. All those who have beta tested the HA-2, we thank you, and we hope that you will contribute immensely to on the HeadFi forums. Your NDAs are over, so if you had any tribulations about posting, don't. Post to your heart's contentment.