Connect with us

Hi, what are you looking for?

Integrated Amps

Krell S-550i Integrated Amplifier

Krell just released the S-550i Integrated Amplifier, which upgrades the performance of their S-300i integrated amp. The new S-550i delivers 275-watts of output, with balanced and single-ended inputs, iPod dock, and Theater Throughput mode to simplify 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.

Krell S-550i Integrated Amplifier - back

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.

Price and Availability
The Krell S-550i Integrated Amplifier is available now for $5,000 in silver and black finishes.


1 pr. balanced via XLR connectors
3 pr. single-ended via RCA connectors
1 dedicated iPod input via 30-pin connector

1 pr. preamp outputs via RCA connectors
1 pr. speaker outputs via gold-plated binding posts

Advertisement. Scroll to continue reading.

Control inputs
1 RS-232 input via 9-pin D-subminiature connector
1 remote IR detector input via 3-conductor 3.5 mm connector
1 12 VDC trigger input via 2-conductor 3.5 mm connector

Control output
1 programmable 12 VDC trigger output (30 mA maximum current) via 2-conductor 3.5 mm connector

Input impedance
Balanced: 95 kΩ
Single-ended: 47.5 kΩ

Frequency response
20 Hz to 20 kHz +0, -0.08 dB

Signal-to-noise ratio
>89 dB, wideband, unweighted, at maximum gain, referred to full power output
>96 dB, “A”-weighted

32.0 dB

Advertisement. Scroll to continue reading.

Input sensitivity
Single-ended or balanced: 1.18 V RMS

Total harmonic distortion
<0.025% at 1 kHz, at 275 W, 8 Ω load
<0.20% at 20 kHz, at 275 W, 8 Ω load

Output power
275 W RMS per channel at 8 Ω
550 W RMS per channel at 4 Ω

Output voltage
133 V peak to peak
47 V RMS

Output current
20 A peak

Slew rate
80 V/μs

Advertisement. Scroll to continue reading.

Output impedance

Damping factor
>110 at 20 Hz, referred to 8 Ω
>75, 20 Hz to 20 kHz, referred to 8 Ω

Power consumption
Standby: 1 W
High-current standby: 40 W
Idle: 90 W
Maximum: 1800 W

Heat output
Standby: 3.4 BTU/hr
High-current standby: 140 BTU/hr
Idle: 310 BTU/hr
Maximum: 2400 BTU/hr

Specifications for preamp only:

6.3 dB (single-ended)

Volume control
Current-mode, 12-bit, discrete R-2R ladder

Advertisement. Scroll to continue reading.

Input overload
Balanced: 12 V RMS
Single-ended: 6 V RMS

Output overload
8 V RMS (single-ended)

Frequency response
20 Hz to 20 kHz +0, -0.05 dB

Total harmonic distortion
<0.009%, 20 Hz to 20 kHz, at 2 V RMS

Signal-to-noise ratio
>87 dB, wideband, unweighted, at maximum gain, referred to 2 V RMS
>94 dB, “A”-weighted

17.26 in W x 5.84 in H x 17.70 in D
438 mm W x 148 mm H x 450 mm D

Advertisement. Scroll to continue reading.

Unit only: 64 lb [29.0 kg]
As shipped: 76 lb [34.4 kg]

Krell S-550i Reviews

From Critics Around the Web

Click to comment

Leave a Reply

Your email address will not be published. Required fields are marked *


Our Reviews

Bookshelf Speakers

The new Lumina collection brings the artistry of Sonus faber loudspeakers to a much wider audience for a lot less money.


BDI sets a high bar with another modern media console designed to conceal all your electronics and a sound bar in an elegant ventilated...


Nobody needs to be reminded that the past four months have taken a toll on our collective psyches; being quarantined for months in New...

LG Electronics

The LG Tone Free Earbuds with Meridian technology include a unique UV-light disinfecting wireless charging case and are undeniably better sounding than AirPods.

LG Electronics

A go-anywhere portable wireless speaker with multi color lighting effects that leaps to the top of its class thanks to Meridian Audio technology.


Rock solid adjustable motorized standing desk that raises or lowers at the touch of a button. Budget priced at only $379.

You May Also Like

Integrated Amps

Exquisitely tuned by the Marantz Sound Master, the MODEL 30 integrated amplifier features a master-curated Marantz HDAM and a fully discrete design for luxurious...

Integrated Amps

Flagship integrated amp featuring Purifi Eigentakt Hybrid Digital amplifier technology, built-in BluOS multi-room streaming, 32-bit DAC, full MQA decoding, and Dirac Room Correction.

Integrated Amps

Stereo Integrated Amps for Audiophiles Yamaha just released reengineered A-S series integrated amplifiers for high-end audio enthusiasts. The new models — A-S1200, A-S2200 and...

Integrated Amps

Audiophile-grade Hi-Res Music Streaming Amp The Marantz PM7000N is the company’s first fully discrete current feedback integrated amplifier with wireless music streaming capabilities and...


ecoustics is the unbiased resource for the latest technology news, coolest gadgets, and best consumer electronics. Plus get product reviews, roundups and deals from all over the web on everything electronic. Read more

Copyright © 1999-2020 ecoustics | Disclaimer: ecoustics may earn a commission when you buy through links on our site.