Astell & Kern AK120 Mastering Quality Sound Dual DAC with AKS01 USB Dock, 64GB MicroSD, ProStudio Optical Audio Connection Kit, and High Speed Travel Charging Kit Astell & Kern AK120 Mastering Quality Digital Music Player with AKS01 Dock, SanDisk 64GB MicroSD card, Buttero Italian Leather Case, Optical Audio Connection Cable with ProStudio High Speed USB Wall Charger Kit. 64GB Internal Storage Expandable up to 192GB (2x 64GB External Miscro SD's) Equipped two high-performance Wolfson WM8740 24bit 192kHz DACs in a dual-mono configuration Can be used as an external DAC or a digital source via USB 2.0 or Optical TOSLINK Plays back DSD, WAV, FLAC, APE (Normal, High, Fast), ALAC, AIFF, WMA, ASF, OGG, AAC & MP3 files