With a power output of 275W per channel into 8ohms, rising to 550W into an 4ohm load, the S-550i comes complete with both single-ended and balanced inputs, a dedicated iPod dock and Krell's Theater Throughput mode, enabling it to be integrated into surround sound systems.
The preamp section is based on Krell's Phantom preamplifier design, with no capacitors in the signal path, discrete balanced circuitry, current mirrors for high linearity and no negative feedback.
The volume control uses a balanced resistor ladder for optimum signal quality and linearity, Krell claiming that 'bandwidth and transient response of the preamp circuitry are virtually unaffected by the volume setting'.
Despite its relatively compact dimensions, the amplifier packs a 1750W transformer and generous power supply capacitor storage, and the power section again uses all-discrete circuity, and like all of the company's power amps is designed as an ideal voltage source, doubling output as speaker impedance halves.
The Krell S-550i has one balanced input, three single-ended inputs on RAC phonos, and a dedicated 30-pin input for the iPod dock supplied. It also has an RS-232 control input, a connection for an external infrared sensor, and 12V trigger inputs and outputs.
Basic iPod control functions are available from the remote control supplied, which can also control a Krell CD player.
Written by Andrew Everard