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I was less than thrilled by Editor-in-Chief Jim Austin's suggestion to review the solid-state Krell K-300i integrated amplifier ($7000, plus an additional $1000 for the optional DAC). I had recently reviewed another $7000 integrated amplifier, the quite different hybrid Aesthetix Mimas, and while I ended up liking the Mimas a whole lot, I felt decidedly lukewarm about having to recalibrate expectations for another integrated, especially one that costs far less than my reference Dan D'Agostino Progression monoblocks ($38,000/pair) and whose DAC option is a fraction of the price of my…
I began with Muddy Waters's "Good Morning Little Schoolgirl" from his 1964 album Folk Singer (24/192 MQA, Chess/Tidal). Timbres were virtually neutral with just a touch of inviting warmth, dimensionality was impressive, and the guitar's cleanly articulated dynamic nuances drew me in. The Krell K-300i sounded great.
I was equally enamored of the reproduction of mezzo-soprano Marianne Crebassa's rendition, with pianist Fazil Say, of Debussy's "La mer est plus belle ques les cathedrals," from their album Secrets (24/96 WAV/Erato 564483). The sound was smooth and inviting—I loved the warm…
Sidebar 1: Krell Designer Dave Goodman on iBias and Other Features
The K-300i uses modern techniques that we've implemented in the recent designs and upgrades we've issued since the split. First, it has a differential current-mode input stage that drives a fairly conventional output stage. Though we've done such designs before, I discovered that by fine-tuning parts of the gain stage I could significantly reduce distortion—specifically the second-harmonic component. The predominant characteristic is now the third harmonic, which we've found makes the K-300i sound much better.
In…
Sidebar 2: Specifications
Description: Solid-state integrated amplifier with iBias, class-AB output stage, and optional D/A module. Analog inputs: 2 balanced (XLR), 3 single-ended (RCA). Optional digital inputs: 1 Toslink optical; 1 S/PDIF coaxial; 2 HDMI (HDMI 2.0a, HDCP 2.2; supports DSD audio and 4K video); 1 USB-A (USB 2.0 host); 1 USB-B (USB 2.0 audio device); 1 Bluetooth with aptX. Outputs: 1 pair speaker outputs; 1 pair single-ended preamplifier outputs (RCA); 1 HDMI output; 1 12V trigger output. Output power: 150Wpc into 8 ohms (21.8dBW), 300Wpc into 4 ohms (21.8dBW). Voltage…
Sidebar 3: Associated Equipment
Digital sources: dCS Rossini DAC & Rossini Clock;
Mytek Brooklyn DAC+; Apple 2017 MacBook Pro computer with 2.8GHz Intel i7, SSD, 16GB RAM; Intel NUC7i7BNH with 8GB RAM, 128GB SSD running Roon; Linksys routers (2), Small Green Computer Systemoptique optical isolation bundle, TP-Link gigabit ethernet media converters plus multimode duplex fiber optic cable (2); Small Green Computer linear power supplies (4) & Small Green Computer 200W Linear Power Supply; external hard drives, SSD USB sticks, iPad Pro.
Power amplifiers: Dan D'Agostino Master…
Sidebar 4: Measurements
I measured the Krell K-300i using my Audio Precision SYS2722 system (see the January 2008 "As We See It"). I usually precondition amplifiers by running them at one- third power into 8 ohms for an hour. The Krell almost made it, turning itself off after 55 minutes, with the front-panel display showing the message "Over temperature left channel." The top panel over the heatsinks was hot, at 142.8°F (61.6°C), but cooler over the transformer at 113.1°F (45.1°C). This is a tough test for an amplifier with a class-AB output stage, as one-third power results in the…
My in-person introduction to Devialet's products was under auspicious circumstances. I was in Paris for what would be a month-long vacation; my wife was there to give some lectures, but I was free to roam the city, take pictures, practice my bad French, and enjoy the excellent food—the experience of a lifetime except that, a few days in, I was missing music. Still early in my visit, I wandered by the big Devialet retail store near the Paris Opera; it was closed but it gave me an idea. I soon had two Gold Phantom powered loudspeakers in our Paris studio apartment.
That was my hands-on…
Because the Expert Pro is such a versatile product—it's basically a music computer that incorporates everything except the music-data source at one end of the system and the loudspeakers at the other—you have to tell it what you want it to do. If you want to use a turntable, you need to set the analog inputs to phono and set the gain and loading parameters appropriate to your cartridge. If you want to use SAM to make loudspeaker-specific adjustments, you'll need to turn that on, choose your loudspeaker from a long list, and assign that function to a button on the remote control. (Because…
Sidebar 1: Specifications
Description: Remote-controlled, solid-state integrated amplifier/streaming DAC with software-assignable inputs, LCD screen, switch- mode power supply, and high-efficiency output stage. Inputs: 1 Ethernet on RJ45; 1 bidirectional USB 2.0; 1 S/PDIF on TosLink; 1 S/PDIF on miniTosLink; 1 pair RCA jacks assignable to MM/ MC phono, line, or two S/PDIF digital inputs. Main outputs: 2 pairs of binding posts. Other inputs/outputs: trigger, SD card (for configuration and firmware). Supported formats: up to 32 bits/192kHz PCM via USB; up to 24 bits/192kHz PCM via Ethernet…
Sidebar 2: Associated Equipment
Analog sources: Thorens TD 124 turntable (reconditioned by Schopper AG), Thomas Schick 12" tonearm; Ortofon Xpression cartridge.
Digital sources: Intel NUC computer running Roon Optimized Core Kit; Synology DS918+ DISKSTATION 4-BAY Network Attached Storage device, aka NAS with 4 WD 4TB Red 5400 rpm SATA III 3.5" Internal Hard Drives and my TP-Link 8-Port Gigabit network switch (unmanaged); Pro-Ject CD Box RS2 T CD Transport; Mytek Brooklyn Bridge Streaming DAC.
Preamplification: Auditorium 23 Standard step-up transformer, EAR 834P phono preamp,…