Krell K-300i Integrated Amp/DAC Lab Report

Lab Report

Based on appearances alone it might be tempting to compare the K-300i with Krell's earlier S-300i [HFN Feb '09] but, in fact, it has much more in common with the Duo series [HFN Oct '14]. Specifically, the K-300i is free of the S-300i's odd-order harmonics while distortion increases with level (0.0016-0.014% over the specified 150W range at 1kHz) rather than decreasing – an atypical scenario – as in the S model. The frequency response is both flatter and more extended with ±1dB limits of <1Hz-95kHz (vs. 4Hz-60kHz for the S-300i), the output impedance is reduced by a factor of four to just 0.018-0.030ohm (20Hz-20kHz) and, most impressive of all, noise is suppressed to the point of achieving an A-wtd S/N ratio of 95.5dB (re. 0dBW).

Power output exceeds the 150W/300W spec. at 2x208W/8ohm and 2x370W/4ohm, with 230W and 450W into 8/4ohm under dynamic conditions. However, despite the potential of that massive toroid, power into low 2 and 1ohm loads is protected at 480W and 288W [see Graph 1, below].

The optional digital board is based on the ESS ES9028 DAC, implemented here with its minimum phase digital filter, free of pre-ringing and offering a 75dB stopband rejection. The A-wtd S/N is some way behind what is achievable with this DAC at 101dB (re. 0dBFs, preamp output at 2V) but jitter is very low at <15psec with all 48kHz-192kHz sample rates. Distortion falls to as low as 0.0002% at 1kHz and 0.001% at 20kHz (re. –10dBFs) and – important from a subjective standpoint – is otherwise very consistent with frequency [see Graph 2, below]. The frequency responses reach out to –0.67dB/45kHz and –2.1dB/90kHz with 96kHz and 192kHz files, respectively. PM


Dynamic power output versus distortion into 8ohm (black trace), 4ohm (red), 2ohm (blue) and 1ohm (green) speaker loads. Max. current is 17.0A


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

Continuous power (<1% THD, 8/4ohm) 208W / 370W
Dynamic power (<1% THD, 8/4/2/1ohm) 230W / 450W / 480W / 288W
Output impedance (20Hz–20kHz) 0.018–0.030ohm (200ohm, pre)
Freq. resp. (20Hz–20kHz/100kHz) +0.0 to –0.11dB/–1.1dB
Digital jitter (48kHz/96kHz) 14psec / 10psec
A-wtd S/N ratio (re. 0dBW/0dBFs) 94.5dB (Analogue) / 100.9dB (Dig)
Dist. (20Hz-20kHz; 0dBW/–20dBFs) 0.00035–0.007%/0.0005–0.001%
Power consumption (idle/rated o/p) 61W / 575W (18W standby)
Dimensions (WHD) / Weight 438x104x462mm / 18.2kg
Price £7500 (£1300 for the digital module)

Krell Industries LLC
Supplied by: Absolute Sounds Ltd
0208 971 3909