Network Audio Players/Servers

A&K’s earlier SP2000T [HFN Jun ’22] included a 4200mAh/3.8V Li-Polymer battery, upgraded to 5050mAh in the SP3000 and now 6780mAh in the SP4000, but this flagship digital audio player still lacks the beef of, for example, iFi Audio’s ‘Transportable’ iDSD Valkyrie DAC/headphone amp [HFN Oct ’25] with its 20,000mAh Li-Polymer power plant.

The latter sustains 2570mW/32ohm and a full 1775mW (1.8W) into very low impedance 8ohm headphones while the SP4000 clips at 380mW/32ohm (or 3.49V) at volume ‘148’ with a peak level (0dBFs) digital input, so the dial should not exceed this value. For the toughest ’phones the SP4000 offers just 161mW/8ohm (volume ‘130’) while 600ohm earbuds have 27mW at their disposal – a full ‘150’ volume setting is possible here with 0dBFs digital inputs without clipping [see Graph, above].

The SP4000’s <1ohm output impedance ensures the system response [see PM's Lab Report] is largely unaffected by swings in headphone load impedance. Distortion does increase slightly when driving lower impedances, however, from 0.001% at 600ohm to 0.007% into 32ohm (all re. 566mV into 20Hz-20kHz, or 10mW/32ohm). And yet, for low noise (6.8µV) and a wide 115dB A-wtd S/N ratio, the SP4000 has a trump card to play against its big-boned competition! PM