Integrated Amplifiers

While the claimed doubling of the latest Diablo’s 333W/8ohm output to 666W/4ohm is not quite met under steady-state conditions, this massive integrated is still exceedingly powerful and offers exceptional (speaker) load tolerance. In practice, it delivers closer to 2x360W and 2x640W into 8 and 4ohm, respectively, with enough in the tank to support 451W, 895W, 1.75kW and 3.05kW into 8, 4, 2 and 1ohm loads (<1% THD) under dynamic conditions [see Graph 1]. Overall gain is a sensible +38.1dB and the A-wtd S/N ratio clocks in at a creditable 92.8dB (re. 0dBW). Distortion is lowest at ~0.01% at 30W/8ohm, increasing at lower and higher power (0.04%/1W and 0.05%/100W, all 1kHz/8ohm) but holds fairly steady with frequency. The response is very flat and extended (just –0.7dB down at 100kHz) but the output impedance of ~0.1ohm may introduce some slight modification depending on speaker load.

Digital inputs are handled by the new ES9039PRO DAC which includes the customary seven user-selectable digital filters. The flattest response is achieved by the Fast Minimum and Linear phase filters at –0.07dB/20kHz, –0.6dB/45kHz and –1.5dB/90kHz with 48kHz, 96kHz and 192kHz digital files, respectively. The 102.5dB A-wtd S/N is limited by the 1V/0dBV tape output but distortion, while low with a minimum of 0.00045% over the top 30dB of its dynamic range [see Graph 2], still shows the 3rd harmonic seen in the main amplifier itself. That said, distortion is, again, remarkably unaffected by frequency while digital jitter is spectacularly low at <5psec with all sample rates. Phase noise is also entirely absent – necessary for pin-sharp imaging – while stereo separation is very wide at >120dB midband. PM