Network Audio Players/Servers

Both the established Stereo 230 amplifier and this new TruStream streamer/DAC employ the same ES9038Q2M chip, both implementations thankfully defaulting to Leak’s preferred ‘Minimum Phase Fast’ digital filter. Arguably, the TruStream’s layout is the better, not least because the DAC’s differential output is driving a balanced analogue stage, the latter offering a maximum 4.15V output (re. 1kHz/0dBFs) from a 54ohm source impedance. Noise is low too, benefitting a wide 115dB A-wtd S/N ratio regardless of network or USB-C/USB-A input. This, in turn, assists in the TruStream’s excellent low-level linearity, the DAC and analogue stage proving good to ±0.2dB over a full 110dB dynamic range. Distortion is low too [see Graph 1, below], falling to a minimum of 0.0001-0.0003% (re. 20Hz-20kHz) over the top 20dB of its dynamic range, with 2nd and 3rd harmonics the main components. The TruStream’s ‘clean sheet’ continues, meanwhile, with its exceptionally low correlated jitter [see Graph 2, below] that remains <10psec across all 48kHz-192kHz sample rates.

As alluded to earlier, the ES9038 DAC includes the option of both programmable and ‘built in’ upsampling/FIR filter coefficients. Leak’s choice of the high-order minimum phase option combines zero pre-ringing with extended post-ringing in the time domain together with a useful 75dB stopband rejection (or 80dB at a 96kHz sample rate). Frequency response(s) extend out to –0.2dB/20kHz, –1.05dB/45kHz and –3.3dB/90kHz with 48kHz, 96kHz and 192kHz files/streams, respectively, while the quality of the analogue stage is further illustrated in the fine >100dB stereo separation (re. 20Hz-20kHz). PM