Integrated Amplifiers

In practice, Eversolo’s choice of TI’s PurePath Class D amplifier module [see Lab Report] means its ‘real world’ performance is more closely aligned with WiiM’s ‘Amp’ [HFN Nov ’24] than costlier streamer/amps using ICEpower’s latest ‘Edge’ technology or anything from the self-oscillating Hypex/Purifi/Eigentakt platform. Consequently, both the Eversolo Play and WiiM Amp betray the foibles of ‘traditional’ analogue Class D amplifiers where the inductive output filter [the screened coils on the bottom left of inside shot on first page] causes a rise in output impedance at high frequencies, lifting from a ‘flat’ 0.065ohm (20Hz-1kHz) to 0.35ohm/10kHz, 1.75ohm/20kHz and 12ohm/50kHz [red trace, Graph below].

As a result, variations in speaker load influence both the system response and distortion. Unloaded, the Play has a significant resonance/response peak of +22dB/48kHz [grey trace, inset Graph]. Into 8ohm [black trace] it rises to +0.7dB/20kHz before peaking at +1.14dB/34kHz, but rolls away into 4ohm to –0.8dB/20kHz [orange] before drooping further to –3.8dB/20kHz into 2ohm [blue] and –7.5dB/20kHz into 1ohm [green]. So the high treble ‘character’ of the Play will inevitably be influenced by your choice of partnering loudspeaker. PM