The AI-503 is an integrated amp and USB DAC that supports inputs up to 11.2MHz DSD and 384kHz/32-bit PCM. The DAC/preamp, which is the heart of the unit, follows the same design concept of our UD-503 and adopts a dual-mono circuit design that is fully balanced. Separate VERITA AK4490 D/A converters - made by Asahi Kasei Microdevices Corporation - are used for the left and right channels. In addition to a USB digital input (for Windows/Mac computers), optical/coaxial digital input and RCA analog input, we have also enabled high-resolution wireless audio listening by including a LDAC-compatible Bluetooth® receiver. Furthermore, with a combined 3.5mm optical digital/stereo mini jack on the front panel, the unit supports wired, as well as wireless, input from DAPs.

The power amplifier uses a Class-D power amplifier (made by ICEpower a/s) that guarantees high resolution during the playback of delicate signals as well as high linearity at high volumes. This unit can power both compact bookshelf speakers (for desktop applications) and large floorstanding speakers. The pre-amp section uses a fully-balanced TEAC-QVCS high-precision volume control circuit with a 4-circuit construction. By maintaining detail levels at all resolutions, the AI-503 creates a very realistic soundstage, along with a high signal-to-noise ratio and excellent sense of space. By connecting an external power amplifier to the fitted pre-out jacks, you can upgrade performance and create an even more capable audio system. The headphone amp section uses a discrete TEAC-HCLD circuit, with a push-pull arrangement, allowing it to drive even high-impedance headphones with ease. The two-stage High/Low gain switch enables optimal volume setting for everything from low-impedance in-ear monitors to high-impedance (600Ω) on-ear headphones. Furthermore, the inclusion of a 3.5mm headphone jack, one that supports a 4-pole separate ground connection, allows excellent channel separation, even when using balanced-type headphones or earphones.