The HM901U from HIFIMAN is a reference-level portable music player that ships with the Musical Amp card and features a number of enhancements resulting in mastering-quality sound for audio engineers, audiophiles, and serious audio enthusiasts. The unit offers up to 256GB of storage via SD card memory and supports multiple music formats including MP3, AAC, WMA, OGG, APE, WAV, FLAC, AIFF, ALAC (M4A), and DSD (DFF).
The HM901U utilizes a pair of ES9018 DAC chips to achieve a wide sound stage and extremely high-detail separation. The analog circuit design utilizes two OPA627 and two OPA2107 op-amps that have been integrated into a highly optimized custom circuit specifically designed for the ES9018 DACs. The dual-voltage battery runs for up to 9 hours and delivers ±7.4V, 2000mA of power, which helps eliminate noise from the power supply and allows you to focus on your music without distractions. An advanced and patented step analog volume control offers precise and accurate channel balance at all levels, particularly at lower volumes, which accommodates highly sensitive in-ear monitors.
The HM901U features a modular approach to headphone amplification by utilizing a user-replaceable slot for amplifier cards. With so many different styles of headphones available, it proved difficult to optimize only one amplifier. The card slot allows the user to integrate the amplifier of their choice, which best complements their style of headphone. The included Musical Amp card uses discrete components that are designed to reveal a mellow and silky vacuum-tube style that excels at classical music, vocals, and jazz performances. The CNC machined enclosure is designed to prevent system crashes due to temperature issues and other disturbances. The HM901U ships with the dual-battery module, a USB cable, an RCA cable, a charger, and the pre-installed Musical Amp card.