Integrated Amplifiers

Like the 250i [HFN Aug '12], this latest '250W' Eloquence 255i integrated will, in fact, deliver far closer to 2x435W/8ohm and 2x680W/4ohm with a thundering 600W and 1137W, respectively, under dynamic conditions. This is fractionally higher than that achieved by the 250i (545W/8ohm and 1010W/4ohm) although the profile of Perreaux's protection regime has also been 'tweaked' so that a higher 1438W is available into 2ohm but a reduced 610W (from 810W) is permissible into 1ohm [see Graph 1]. PSU noise was higher in this sample of the 255i than the 250i measured six years ago (–68dBV to –60dBV), with the A-wtd S/N now reduced to 76.5dB from 81.5dB (re. 0dBW). This PSU noise also impacted the jitter/intermodulation performance of the new DAC module, accounting for most of the 1315psec (48kHz) and 790psec (96kHz) that was measured.

That aside, the 255i has fractionally higher (but not 'high') distortion at ~0.0025% versus ~0.0019% through the midrange over its full 1-250W rated bandwidth, but with the same impressively consistent ~0.01% THD up to 20kHz. The low 0.013ohm output impedance, increasing to 0.06ohm at 20kHz and 0.33ohm at 100kHz is unchanged as is the response – still flat from 1Hz up to 20kHz (–0.05dB) and 100kHz (–1.3dB) with very little drop-off into low impedances (just –0.55dB/20kHz into 1ohm). The digital board, based on an ESS9038 DAC with minimum phase filter selected by Perreaux, offers very low distortion of just 0.0003-0.0017% (20Hz-20kHz, 0dBFs), with a minimum of 0.0002% [see Graph 2] and with response limits of –0.02dB/20kHz, –0.2dB/45kHz and –0.6dB/90kHz with 48kHz, 96kHz and 192kHz media, respectively. PM

Continuous power (<1% THD, 8/4ohm): 435W / 680W
Dynamic power (<1% THD, 8/4/2/1ohm): 600W / 1137W / 1438W / 610W
Output impedance (20Hz–20kHz): 0.013–0.065ohm (210ohm, pre)
Freq. resp. (20Hz–20kHz/100kHz): +0.0 to –0.1dB/–1.3dB
Digital jitter (S/PDIF at 48kHz/96kHz): 1315psec / 790psec
A-wtd S/N ratio (re. 0dBW/0dBFs): 76.5dB (Analogue) / 100.1dB (Dig)
Dist. (20Hz-20kHz; 0dBW/–20dBFs): 0.0027–0.009%/0.0003–0.0017%
Power consumption (idle/rated o/p): 84W / 1030W (1W standby)
Dimensions (WHD) / Weight: 426x149x344mm / 25kg
Price: £6895-£8820