Musical Fidelity M8xi Integrated Amp/DAC Lab Report

Lab Report

Care needs to be taken with the bridged/floating output of this very high power amplifier – it must never be connected to an active or grounded speaker/sub solution or either one may be damaged. Standard passive speakers are just fine, of course, where the M8xi sails past its rated 550W/8ohm output to deliver 640W/8ohm and 940W/4ohm with sufficient headroom to accommodate peaks of 880W, 1740W and 1300W into 8, 4 and 2ohm loads under dynamic conditions [see Graph 1, below]. There's a sensible current limit of 26.8A (<1% THD) so power is 'restricted' to 720W/1ohm. The overall gain of the M8xi is also 'sensible' at +37dB, lower than the +43dB typically encountered, but yielding a far more useable volume range with standard 2V line level sources. The A-wtd S/N ratio is a little above average at 86dB (re. 0dBW) and distortion very low at 0.0009–0.0035% (10W, 20Hz-20kHz), although there is a slight increase in THD at low power levels (~0.004% at 1kHz/1W/8ohm) and progressively higher power levels from 0.0015%/10W to 0.003%/100W, 0.005%/250W and 0.006%/500W (all 1kHz/8ohm). The frequency response is not quite as flat as MF's spec. suggests, but –0.4dB/20Hz to –0.25dB/20kHz and –4.1dB/100kHz is still fine.

Maximum (DAC) line output here is 1.9V from a 50ohm source impedance (rising to 220ohm/20Hz), the stage offering a generous 107dB A-wtd S/N ratio and a response that extends to –0.05dB/20kHz with CD/48kHz media and –0.9dB/45kHz (96kHz files) and –3.1dB/90kHz (192kHz files). Jitter is well suppressed (typically 10-200psec) and distortion is held to 0.001% across the top 30dB of its dynamic range through bass and midrange, rising to 0.005-0.1% at 20kHz [Graph 2, below]. PM


Dynamic power output versus distortion into 8ohm (black trace), 4ohm (red), 2ohm (blue) and 1ohm (green) speaker loads. Max. current is 26.8A


Distortion vs. USB 24-bit digital signal level over a 120dB range at 1kHz (black) and 20kHz (blue)

Continuous power (<1% THD, 8/4ohm) 640W / 940W
Dynamic power (<1% THD, 8/4/2/1ohm) 880W / 1740W / 1300W / 720W
Output impedance (20Hz–20kHz) 0.039–0.11ohm (48-220ohm, line)
Freq. resp. (20Hz–20kHz/100kHz) +0.0 to –0.3dB/–4.1dB
Digital jitter (USB at 48kHz/96kHz) <10psec / 210psec
A-wtd S/N ratio (re. 0dBW/0dBFs) 85.9dB (Analogue) / 107.1dB (Dig)
Distortion (20Hz-20kHz; 10W/–3dBFs) 0.0009–0.0035%/0.0008–0.11%
Power consumption (idle/rated o/p) 133W / 2.1kW
Dimensions (WHD) / Weight 485x180x500mm / 46kg
Price £5649

Musical Fidelity (Audio Tuning Vertriebs GmbH)
Supplied by: Henley Audio Ltd, UK
01235 511166