Description: Stereo class-AB integrated amplifier with optional streaming DAC. Analog inputs: 3 pair XLR. Digital inputs: Ethernet, USB (4), AES (adaptable to S/ PDIF), TosLink, Wi-Fi. DAC accepts PCM up to 32/384, DSD up to DSD128. All files are upsampled and oversampled to a data rate of 192kHz, and data is moved asynchronously. Loudspeaker outputs: stereo pair 0.25" binding posts. Input voltage at max volume: 1.14V for maximum rated output at full rated power. Continuous maximum power output: 200Wpc into 8 ohms (23dBW), 400Wpc into 4 ohms (23dBW). Peak power…
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Sidebar 2: Associated Equipment
Digital sources: dCS Rossini DAC and Rossini Clock; Synology 5-bay 1019+ NAS; Roon Nucleus+ music server, Uptone Audio etherRegen, Small Green Computer Sonore opticalModules (2) and Deluxe opticalModule, Linksys routers (2), and Arris modem, all powered by HDPlex 300 four-component linear power supplies (3); iPad Pro; Apple 2017 MacBook Pro computer with 2.8GHz Intel i7, SSD, 16GB RAM.
Preamplifier: Dan D'Agostino Momentum HD.
Power amplifiers: Dan D'Agostino Progression monoblocks.
Integrated amplifier: Krell K-300i.
Loudspeakers: Wilson…
Sidebar 3: Measurements
I tested the Boulder 866 with my Audio Precision SYS2722 system (see the January 2008 "As We See It"), then repeated some tests with the magazine's more recently acquired APx555 system. But first, I preconditioned the amplifier by following the CEA's recommendation of operating it at one-eighth the specified power into 8 ohms for 30 minutes. At the end of that time, the top panel was very hot, at 115.5°F (44.2°C), and the heatsinks were too hot to touch, at 133.3°F (56.3°C). The Boulder amplifier's output stages appear to be biased heavily into partial class-A…
Naim Audio
One summer afternoon in Brooklyn, after a sweaty too-long day doing construction, I stumbled upon a hi-fi shop I'd never noticed before. I thought, hmmm, I bet they have air conditioning.
One summer afternoon in Brooklyn, after a sweaty too-long day doing construction, I stumbled upon a hi-fi shop I'd never noticed before. I thought, hmmm, I bet they have air conditioning.
Inside, the air was only marginally cooler, but before I could leave, an excessively happy salesman introduced himself. After a bit of low-level chit-chat, he asked me if I was into British audio. I told him I "Never heard of it."
After flashing a condescending smile, he directed me to a stark, nearly empty demonstration room (that I hoped had working AC) and showed me an unusual-…
The Atom's line stage: In order to get a feel for the driving power of the Uniti Atom's line stage, I connected my Dr. Feickert Analogue Blackbird turntable, equipped with a 10.5" Schick arm and a Koetsu Rosewood Signature Platinum moving coil cartridge, which sent its current to my EMIA 1:10 step-up transformer driving the tubed Tavish Design Adagio phono stage. My goal: to see how the Naim preamp section compared to my reference Rogue Audio RP-7 line-level amplifier, which, at $4995, costs 50% more than the $3290 Uniti Atom HE. I spent days using this Blackbird-Atom combo to explore every…
Phono preamplifiers could be compared to children as viewed by a previous generation of adults: They are expected to be small in stature, and they should stay out of the way, seen but not heard and maybe not even seen. With the simpler models typically encountered at lower price points, there's little to do except "set it and forget it."
But a phono preamplifier such as the component under review—the Pro-Ject Phono Box RS2 ($1999)—could, with its many features, keep you up all night, playing. A component like the RS2 can increase your hands-on involvement with your vinyl playback, which…
Acoustic guitar strumming stood out more in the mix, but overall presentation was not quite as immersive. For the first time, I noticed a female backup singer "woo-oohing" behind Bird's whistling.
On the blues-tinged "Bloodless," with loading set to 200 ohms, Bird's five-string violin pizzicato plucking shone with substance and body. But with loading at 400 ohms, an increased sense of air gave most instruments pleasing purity, without excessive politesse. Piano key strikes sounded clean and refined. Bird's pizzicato felt more exciting on the attacks—so present and convincing it gave me…
Sidebar 1: Specifications
Description: Solid-state MC/MM phono preamplifier, fully balanced dual-mono design. Inputs: 1 balanced XLR, 1 unbalanced RCA. Outputs: 1 XLR, 1 RCA. Gain MC: (RCA) 60, 63, 66, 70dB. Gain MM: (RCA) 40, 43, 46, 50dB. Input impedance loading continuously variable 10–1000 ohms, MC; 47k ohms fixed, MM. Capacitance (switchable): 50, 100, 150, 200, 250, 300, 350, 400pF. Signal/Noise: MM (40dB): 89dB A-weighted (10mV); MC (60dB): 79dB A-weighted (1mV). THD: <0.0015% (MM 40dB, 1 kHz); <0.0024% (MC 60dB, 1 kHz). RIAA accuracy: within 0.4dB/20Hz–20kHz. Subsonic filter…
Sidebar 2: Associated Equipment
Analog sources: Clearaudio Performance DC Wood turntable with Tracer tonearm and Talisman v2 MC cartridge; MoFi Electronics UltraDeck+ turntable with tonearm and StudioTracker MM cartridge and weight.
Preamplification: MoFi Electronics StudioPhono phono preamplifier, MBL N11 preamplifier.
Power amplifiers: MBL C15 monoblocks.
Integrated amplifiers: MBL N51, VAC Sigma 170i.
Loudspeakers: MBL 120, Chario Aviation Amelia.
Cables: Ansuz Acoustics D2, AudioQuest NRG, and Morrow Audio (some interconnects).
Accessories: AudioQuest Niagara…
Sidebar 3: Measurements
The Pro-Ject Phono Box RS2 phono preamplifier is a very complicated product. It has balanced and single-ended inputs; balanced and single-ended outputs; four different voltage gain settings and multiple choices for capacitive loadings in MM mode; four different gain settings and continuously variable input impedance in MC mode; and standard switch-mode and upgrade linear power supply options. I performed a complete set of measurements with my Audio Precision SYS2722 system (see the January 2008 "As We See It"), using the balanced input and output with the preamp…