Krell S-550I 275 Watt Integrated Amplifier Now Shipping


There is just something cool about a company that is named after an extinct race of advanced aliens from the planet Altair IV.  Yes, I’m talking about Krell, which got its name from the classic 1956 science fiction film, Forbidden Planet.

Aside from its place in sci-fi lore, the name Krell has been synonymous with high end, high powered, and high-performance gear for years.  Krell recently showed off some slick new gear at CES including a new 7.1 pre-pro that features 10 HDMI input, balanced audio and more.

Now, one of their new products, the S-550i Integrated Amplifiers will begin shipping this week. Building on the success of the award winning S-300i integrated amplifier.  According to Krell, the S-550i Integrated Amplifier boasts the sound quality and power output capable of driving any loudspeaker to its maximum performance.
Delivering 275 watts of output, the S-550i Integrated Amplifier is a robust power source for any speaker and only occupies a fraction of the space typically required for a system delivering this performance. The S-550i Integrated Amplifier is outfitted with balanced and single-ended inputs, iPod dock, and Theater Throughput™ mode. Developed by Krell, Theater Throughput™ simplifies integration into home theater systems. For custom integration applications, 12 Volt triggers, RS-232 connectivity and rack mount ears are included. Operational parameters can be customized via the menu system that is accessible from the front panel or the included brushed Aluminum remote control.

Preamplifier Highlights 

The preamplifier section features circuit concepts from Krell’s flagship Phantom preamp. Krell Current Mode provides unequaled bandwidth for the most revealing playback of today’s high-resolution music sources. Direct coupled circuitry eliminates impact-robbing capacitors from the signal path and an elegant, custom-machined level control adjusts volume. Discrete circuitry, in a balanced topology, is afforded its own power supply regulation. All signal gain is realized using surface mount technology featuring proprietary current mirrors with nearly 500 times the open loop linearity of other designs. Negative feedback is not used anywhere in the preamplifier, nor is it necessary. Open-loop distortion is typically less than 0.003%. The volume control is realized with a balanced resistor ladder – bandwidth and transient response of the preamp circuitry are virtually unaffected by the volume setting.

Power Amplifier Highlights

The S-550i packs a massive 1,750 watt transformer and 68,000?F of capacitance into an elegant 5″ high chassis. This power supply feeds classic Krell circuitry throughout the topology using only discrete circuitry. As with all Krell amplifiers, the S-550i design is an ideal voltage source. That is, the S-550i doubles its power output when a speaker’s impedance is halved. For the S-550i, the results are 275 watts into 8 Ohms and 550 watts into 4 ohms both channels driven. This capability is essential for realistic reproduction of a recording’s dynamic content. Most amplifiers can’t deliver this power doubling, leaving music sounding compressed and lifeless.

Krell products aren’t cheap, but they sure are amazing.  The S-550i Integrated Amplifier retails for $5,000 and is available now in silver and black finishes.  For more information, please visit or call 203-298-4020.