Pre/Power Amplifiers

While this ‘poweramp’ version of the EVO 300 Hybrid is clearly derived from the earlier integrated model [see boxout], and the respective power outputs are largely unchanged, the distortion via the new transformer-coupled XLR input is very different from that of the RCA input. So the sound via the RCAs will be consistent between the EVO 300 Hybrid ‘integrated’ and ‘poweramp’, but the latter’s XLR input will be different...

Tested via the XLRs, the EVO 300 Hybrid offers +29.7dB gain in ‘High’ mode and +23.9dB in ‘Low’ mode, the latter perfectly sufficient for use with any likely partnering preamplifier. Power matches the EVO 300 Hybrid integrated at 2x120W/8ohm and 2x190W/4ohm with 120W, 215W, 340W and 375W into 8, 4, 2 and 1ohm loads, respectively, at <1% THD under dynamic conditions [see Graph 1, below]. The ‘linear’ increase in THD with output is also clear here, from 0.065%/1W to 0.2%/10W and 0.65% at the rated 100W (all 1kHz/8ohm under continuous conditions) versus 0.003%/1W, 0.02%/10W and 0.12%/100W from the integrated and ‘poweramp’ when driven via their RCAs. Versus frequency, distortion is impressively uniform [Graph 2].

Avoiding the need to buffer a volume control also endows the EVO 300 Hybrid ‘poweramp’ with a flatter response (–0.1dB/20kHz and –0.6dB/100kHz compared to –0.4dB/20kHz and –5.6dB/100kHz) even though the amp’s 0.03-0.095ohm output impedance is little changed. Deleting the volume and input switching circuits also improves stereo separation by up to 25dB here at mid and high frequencies. The same casework, PSUs and tubes also brings a consistent residual noise – both amplifiers delivering a worthy 88dB A-wtd S/N ratio (re. 0dBW). PM