TEAC 503 DAC headphone amp or streamer


The follow-up to 2014’s UD-501 , the UD-503 is a USB DAC/headphone amplifier that retains its predecessor’s dual-mono architecture and incorporates a high quality headphone amplifier with balanced/unbalanced outputs. Decoding high-res digital audio is, of course, its prime purpose. This it does with a pair of AKM VERITA AK4490 digital to analogue converters. Part of a family of components developed by AKM for pro audio and high-end audiophile applications, these DACs were purpose-designed for hi-resolution audio, with full support for 11.2MHz DSD and 384kHz/32-bit PCM audio signals.

The fully dual-mono architecture (with one transformer per channel), along with differential processing from DAC to output stage, “minimises any chance of mutual interference to signals and results in the virtual elimination of common-mode noise.” Fully asynchronous USB transfer allows the UD-503 to control and sync incoming PCM and DSD audio signals using precision 44.1kHz and 48kHz clocks. Unusually, users can go one better by adding an external 10MHz master clock, for even greater precision.

teac ud 503 blk

Rather than buy an off-the-shelf solution TEAC has programmed its own FPGA IC to handle DSD signal augmentation. So CD bit length/sample rate signals (44.1kHz/16-bit) and 48kHz PCM files can be converted to DSD, “adding a sense of ‘air’ that is otherwise usually absent”. With four types of PCM and two types of DSD filter there’s plenty of scope for further fine-tuning. In a first for TEAC a digital isolator is employed to completely segregate the digital and analogue circuits, “preventing noise from an external device using the USB input polluting the UD-503’s power supply”. With a set of analogue inputs and a 256-step volume control the UD-503 can act as a standalone pre-amp in a hifi system, either partnered with power amps or active speakers. TEAC has redesigned its HCLD output buffer circuit optimising it for both balanced/unbalanced output.

The UD-503’s HCLD (High Current Line Driver) circuit supports single-ended, balanced and active GND modes. The latter is a new drive method that (via an amplifier circuit) forcibly connects the headphone ‘negative’ to a stable 0v ground. The result is an even lower noise floor and “increased sonic insight”. The UD-503 has a precision-engineered, full-metal A4-sized body, supported by three internally-spiked ‘pinpoint-type’ feet.

You’ve just read about the UD-503. Now imagine a variation on that theme which puts the emphasis on hi-res audio streaming via a network/Bluetooth and streaming audio services such as Spotify and Deezer. That’s essentially describes the NT-503DAB USB DAC/Network Player (with added DAB/DAB+ reception). The NT-503DAB builds on the UD-503’s rear USB input by also adding the ability to handle high-res audio streaming via a network. DLNA 1.5 compatibility means that formats such as DSD (5.6MHz) and 192kHz/24-bit WAV/FLAC can be replayed from PC or NAS (Network Attached Server), all controlled via free TEAC apps for iOS and Android.

teac NT 503DAB blk

Housed in the same size enclosure as the UD-503 the NT-503DAB exchanges one of that model’s headphone outputs for a USB input that’s capable of receiving hi-res audio (5.6MHz/192kHz PCM files) on USB flash memory. There’s also direct, built-in support for DAB/DAB+ digital radio broadcasts, popular paid-for subscription music services such as Spotify and Deezer and the free TuneIn internet radio portal, which gives access to 100,000 stations and 4 million podcasts. Last but not least there’s onboard aptX Bluetooth, to allow music streaming from your smartphone or tablet. The single-headphone output on the NT-503DAB makes use of TEAC’s HCLD circuit to deliver “mostly Class-A performance” for single-ended headphones of up to 600 Ohms impedance. 

UD-503 DAC/Headphone Amplifier £700 (available in black or silver now). NT-503DAB USB DAC/Network Player £950 (available in black or silver, at the end of November)

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