Krell K-300i

Krell is one of the most distinguished names in amplification, so a sub-$10,000 Krell is something to get excited about.

When we heard that Krell had released what it called ‘its most affordable amplifier yet’, and that it featured not only Krell’s famous iBias and XD circuitry, but could also be optionally equipped with a module that adds digital inputs, wireless and streaming capabilities, we got excited… very excited.

Equipment
The Krell K-300i’s front panel looks very sleek, very slick and very modern partly because there’s no rotary volume control. Volume is controlled by pressing one of two buttons on the front panel, or on the handsome remote control that’s included in the price. But the K-300i has other options for volume control, because it has a web server built-in that enables you to control it completely — including volume — from your mobile phone or computer or, indeed, any device that can run a web browser (Chrome, Internet Explorer etc).

As you’d expect from Krell, the new K-300i is powerful, with Krell rating its output at 300W per channel into 4 ohms and 150W per channel into 8 ohms. It also has ‘clever’ input circuitry so that, for example, instead of sticking with boring old input names (Input 1, Input 2 etc), you can re-name each input to better reflect what’s actually connected to it. It has five analogue line-level inputs: two balanced (XLR) and three unbalanced (RCA). You can also adjust input sensitivity for each of these so you don’t get differences in volume when switching from one input to another. Krell calls this ‘Level Trim’, and you can adjust levels across a massive 20dB range (±10dB). There is no phono input.

Confusingly, there’s a second ‘Level Trim’ mode that is used to adjust the output level of the pre-amp outputs (which are unbalanced) across a 20dB range. This would be useful if you’re using some kind of dual-amplifier set-up and your external amplifier doesn’t have its own volume control. The pre-amp output voltage can be set to be fixed (with the voltage set by the Level Trim circuit) or adjustable, so that the voltage tracks changes made using the K-300i’s volume control. Because the Krell doesn’t have Rec Out terminals, you could use the ‘fixed’ setting of the pre-amp output to substitute as a Record Out.

Optional Digital Module
Two versions of the Krell K-300i are available: as a ‘standard’ integrated analogue-only amplifier, which retails for just under ten grand, or with a digital module installed, which retails for $11,999. (There’s no cost penalty if you decide to add the digital module at some later date: it retails for $1999.)

Adding the digital module enables the functionality of the USB-A connector on the front panel (which otherwise doesn’t work at all), and adds a USB-B connector to the rear panel, along with coaxial, optical and two HDMI 2.0a digital inputs, plus one HDMI output. It also adds Bluetooth (with aptX) wireless streaming. The digital module allows Ethernet streaming if you use the free ‘mconnect Control app’ to access streaming services in your area such as Spotify, Tidal, Deezer, etc. The module is Roon-ready, and can play back MQA files plus PCM up to 24/192kHz and DSD128.

Krell’s iBias & XD
Krell’s ‘intelligent’ bias circuit differs from all we have previously encountered that are used to apply bias voltage to the output transistors, because not only does it vary that voltage continuously according to the demands of the audio signal, it calculates the exact voltage by monitoring the output current of the amplifier, rather than the input voltage. According to Krell: “Because iBias Class A measures the output current, the real-time demands of the specific speaker connected to the amp are directly incorporated into the circuit function. In addition, iBias Class A even reduces the bias when the signal is at very low levels, making its operation undetectable by ear and even by standard amplifier measurements. This seemingly small change in topology results in a dramatic improvement in sound quality, especially midrange richness and purity.”

As for the ‘XD’ circuitry that enables the K-300i to have a very low output impedance
(less than 0.035 ohms) right across the audio band (and thus a high damping factor), we can’t tell you anything at all about it because when we asked Dave Goodman, Krell’s Director of Product Development, he replied: “the circuit design is proprietary”.

Listening Sessions
We started playing the new album ‘Stay Around’ which is strangely advertised as “the first posthumous release” from J.J. Cale, which seems to presume he might be releasing a few more ‘posthumous’ releases. We knew that J.J. Cale always avoided publicity, but this seems to be taking it to extremes. Anyway, the Krell K-300i was an ideal vehicle to deliver his songs, because although it’s all laid-back and bluesy, there’s a lot of instrumental sounds to reproduce and a lot of musicianship going on, because it seemed that anyone who was anyone wanted to play with J.J., most famously Eric Clapton and Mark Knopfler. The sound of the Krell K-300i was not only totally transparent, it also separated the threads of the music at the same time it integrated them, so every instrument, every vocal was in its own acoustic space. For tracks that were obviously never intended for release, the sound quality is unbelievably good; just listen to the drums and bass on Stay Around, or the guitar on Oh My. In fact, listen to everything on Oh My, because it’s been recorded as a ‘dry’ probably as a demo, so there’s no prettying-up or ‘production’. The recording of Cale’s voice, for example, on this track is incredible.

This isn’t true of all the tracks, mind you: My Baby Blues is overproduced and sounds a bit muddy. But just listen to the brush-work and piano sound on Tell Daddy, which is a great song… how did this never makeit onto an album while J.J. was still with us? But just as the Krell K-300i was able to reveal the sonic diamonds contained within ‘Stay Around’, it was absolutely ruthless in revealing the dross, perhaps most notably the J.J.’s impossibly badly recorded vocal on Don’t Call Me Joe.

The album caused us to pull out some vintage J.J. Cale, and once again the sonic purity of the Krell K-300i was in clear evidence. Songs you just can’t not own, such as Magnolia, After Midnight, Crazy Momma, City Girls and, of course, Cocaine were made tangibly real by the Krell K-300i.

As for there being plenty of power available, just listen to the depth-charge bass on Moodyman’s I’ll Provide, from his new album ‘Sinner’. Turn up the volume at the peril of your speakers, because the beats come from nowhere — there’s no warning of the aural assaults on your ears. But if your speakers can take the power, you’ll wonder at the cleanliness of the bass, as well as the absolute silence of the backgrounds. This is one hell of a quiet amplifier! The control the Krell K-300i exerted over our bass drivers was testament to the efficacy of the XD circuitry. If this is it working its magic, bring it on, we say, because our speakers never sounded better. The Krell K-300i can mix it up across the octaves too: witness Deeper Shadow (with the pipes of Sadie Walker no less) on the same album.

The Krell K-300i’s ability to articulate female vocals was amply demonstrated listening to Norah Jones’ latest album ‘Begin Again’, though when we say ‘album’ it’s a collection of singles that Jones had already released, but since we don’t follow her slavishly, we hadn’t previously heard them. And we liked what we heard. It’s nothing like the inoffensive [Surely ‘offensive’.?.. Ed] ‘dinner-party’ jazz she toyed with that turned many audiophiles away (particularly when heard for the millionth time at an audio show). But if you want to hear Jones at her best, buy her 2012 album ‘Little Broken Hearts’… you won’t regret the investment.

Conclusion
A Krell integrated amplifier that doesn’t have a five-figure price tag attached? And it has iBias and XD? And a five-year warranty? And it’s made entirely in the USA? And it sounds just like a Krell should? What else could you ever need to know?!

Krell K-300i integrated amplifier
Price: $9999 (add $2000 for digital module)

+ iBias circuit
+ Web server control
+ Digital module

- No phono inputs
- Headphone output

Power output: 150W into 8 ohms; 300W into 4 ohms
Output current: 13A (peak)
Frequency resp.: 20Hz–20kHz ±0.11dB
Frequency resp.: <10Hz–100kHz –0.57dB
S/N ratio (unweighted): >104dB
S/N ratio (A-weighted): >117dB
Gain: 25dB
THD: <0.015%
Slew rate: 46V/µs
Output impedance: <0.035 ohms, 20Hz–20kHz)
Damping factor: >228
Input impedance: 16kΩ (balanced); 8kΩ (unbalanced)
Power consumption (Standby): 11W
Power consumption (Idle): 4W
Power consumption (Max): 900W
Dimensions (whd): 438 × 105 × 457mm
Weight: 23.6kg