Krell S-550i

Amplifier

Long ago I had my heart set on buying a high-power amplifier but could not decide between a Mark Levinson and a Threshold. But I was dreaming rather than saving, because I couldn’t afford either. Then in 1980 along came the Krell KSA-100, a stereo Class-A amplifier that could deliver 1,600-watts into a single ohm. This power output level was unheard of at the time (and is still rare!). I heard a KSA-100 at an Australian Hi-Fi Show in Sydney, and wanted one, because it sounded fabulous. I wanted one so badly I started saving seriously, but another romance intervened, and the money was re-purposed by she who would in time become my better half.

Since then, Krell prices have easily kept pace with inflation and other costs, so few have been able to afford one. However, the introduction first of the Krell S-300i (a 150-watter), and now the Krell S-550i (rated at 275-watts per channel), have been gamechangers for this US-based company, because for the first time, Krell amplifiers have become affordable. The S-550i is still not exactly what you’d call ‘inexpensive’ but it’s certainly within the reach of any audiophile who’s being paid a smidgin more than the ‘average’ Australian wage.

The equipmenT

Krell has always eschewed ‘pretty’ chassis in favour of stark ‘industrial’ exteriors, to the extent that its early power amplifiers—such as the aforementioned KSA-100—were all sharp edges and unfinished aluminium. The S-550i isn’t quite as industrial as the KSA-100, but it’s also not exactly pretty… its looks fall somewhere between the two, so let’s compromise on the expression that it looks ‘business-like’.

Although the Krell comes with a remote control (and what a remote it is, about which more later!), everything you could sensibly expect to control on the amplifier is able to be controlled via the front panel alone, which is eminently sensible. Pushbuttons let you switch between five different inputs, labelled S1, S2, S3, B1 and iPod. The ‘S’ (Source) buttons select the associated unbalanced RCA input terminals on the rear panel. The ‘B’ button selects a pair of balanced XLR input terminals on the rear panel and the iPod input selects a balanced stereo iPod input via a locking 30-pin connector on the rear panel. Krell provides an iPod dock to plug into this, so unlike many amplifiers, no ‘extra’ purchase is required. The dock will accommodate only older iDevices, and not any of the newer Apple devices with Lightning connectors. (And don’t bother waiting for an S-550i with a Lightning connector: Krell says it currently has no plans to make such a dock.) When you select any input, your choice is displayed in the dot-matrix display panel at the right of the front panel.

To the right of the source selector buttons is a mute button that instantly mutes the