PS AUDIO SPROUT

摘要

While not quite as powerful as the Quad Vena [HRV Jan '15], the PS Audio Sprout does meet its 50W specification provided we assume this is into 4ohm where it reaches 68W. A figure of 2x38W is more realistic into 8ohm while its limited headroom amounts to 41W, 77W, 82W and 44W into 8,4, 2 and 1ohm loads under dynamic conditions [see Graph 1, below]. However, the real issue is not power but noise and the tailoring of its (low) frequency response. Under test, a layer of 'hash' or 'grass' was exposed extending right through the 20Hz-20kHz audio spectrum, reducing the A-wtd S/N ratio to just 65.5dB (re. 0dBW) and to 80dB via the USB input/line output (re. OdBFs). in addition, while the DAC/line out already has a filtered LF response that rolls steeply away below 100Hz to reach -5.5dB/20Hz, this is further filtered by the power amp which falls to -25dB/20Hz (but not before a +5.7dB 'bump' provides a kick in the bass at 70Hz...). However, the Sprout's top-end response does not show the speaker load sensitivity of those amps still using balanced Class D modules, and stretches out to -0.3dB/20kHz and -7.4dB/100kHz into 8ohm and 4ohm loads.