Integrated Amplifiers

The last Aesthetix amplifier tested here was the mighty Atlas Signature [HFN Dec '14] and, like that tube/transistor hybrid, the new Mimas's continuous power output is also generously in excess of Aesthetix's 150W/300W 8/4ohm rating at 230W/385W, respectively. Similarly, its A-wtd S/N ratio is a little below average at 81dB (re. 0dBW) while its output impedance is uniformly high at 0.24-0.26ohm from 20Hz-20kHz. The latter will cause some modification of the amp/speaker system response depending on the impedance trend of the speaker itself but this, the moderate noise and very high +48dB overall gain are all functions of Aesthetix's very sparing use of compensatory feedback. Distortion, while impressively uniform with frequency [see Graph 2, below], increases steadily with power output from 0.011%/1W to 0.036%/10W, 0.11/100W and 0.15% at the rated 150W/8ohm.

The distortion behaviour under dynamic conditions is less predictable [see Graph 1, above], reinforcing the fact that the solid-state balanced bridged output is probably injecting more 'colour' into the performance than its tube preamp stage. Nevertheless output is prodigious under transient, music-like conditions where a full 265W, 510W, 780W and 750W (or 27.4A) was recorded up to 1% THD into 8, 4, 2 and 1ohm loads, respectively. So the Mimas really is a powerhouse, its 135W idle power consumption falling to a still-significant 53W in 'normal standby' setting (1-2W would be standard here)! Finally, the stepped attenuator volume control is accurate to ±0.05dB over the top 60dB of its dynamic range while channel separation is a fine >100dB through bass and midrange. PM