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Arcam irDAC-II D/A processor Page 2

Listening with Headphones
As it did in the big rig, the Arcam irDAC-II's headphone output offered, in absolute terms, a somewhat light balance combined with clean highs and an excellent presentation of recorded detail. It worked well with both the Audeze LCD-X and AudioQuest NightHawk headphones, less so with the Thinksound On2s, where the highs sounded a little aggressive. However, it could readily swing enough volts to drive the high-impedance Sennheiser HD650s to satisfying levels. But I needed to hear how it compared with other D/A headphone amplifiers.

The perfect comparison…

Arcam irDAC-II D/A processor Specifications

Sidebar 1: Specifications

Description: D/A processor & headphone amplifier with volume control. Digital inputs: 2 coaxial (RCA), 2 TosLink, 1 USB (Type B), 1 Bluetooth. Analog outputs: 1 pair unbalanced, fixed output (RCA); 1 pair unbalanced, variable output (RCA); 1 headphone (3.5mm). Digital formats supported: 16–24-bit/32–384kHz, PCM; DSD64/128, USB; 16–24/32–96, TosLink; 16–24/32–192, coax; SBC, aptX, aptX-Ll, AAC, Bluetooth. Frequency response: 20Hz–20kHz, ±0.05dB. THD+N: 0.0007% ref. 0dBFS. Signal/noise (A-weighted): 115dB. Maximum output level: 2.15V RMS, line; 4V RMS,…

Arcam irDAC-II D/A processor Associated Equipment

Sidebar 2: Associated Equipment

Digital Sources: Aurender N10 music server (big rig); Antipodes DX (desktop system, headphones); Meridian Explorer USB D/A processor; AudioQuest JitterBug, UpTone Audio ReGen USB cleaner-uppers; MacBook Pro running Pure Music 3.
Power Amplifiers: MBL Corona C15 monoblocks.
Loudspeakers: KEF LS50, Rockport Technologies Avior II.
Headphones: Audeze LCD-X, AudioQuest NightHawk, Sennheiser HD-650, Thinksound On-2.
Cables: Digital: AudioQuest Coffee, Belkin Gold, USB; Monster 3.5mm–TosLink, S/PDIF optical. Interconnect (unbalanced): AudioQuest…

Arcam irDAC-II D/A processor Measurements

Sidebar 3: Measurements

I measured the Arcam irDAC-II with my Audio Precision SYS2722 system (see the January 2008 As We See It"), using the Audio Precision's optical and electrical digital outputs, USB data sourced from my MacBook Pro running on battery power with Pure Music 3.0 playing WAV and AIFF test-tone files, and with the same files played on an iPhone 6S, an iPad2, and an HTC Android phone via Bluetooth. Apple's USB Prober utility identified the irDAC-II as "irDAC-II" from "ARCAM," and revealed that its USB port operated in the optimal isochronous asynchronous mode. Apple's…

Lamm Industries L2.1 Reference preamplifier

"As the original L2 circuitry was virtually flawless, it was the emergence of new electronic components that opened up a possibility of [even better performance] . . ."

So begins one of two booklets—one a collection of specifications and interior photos, the other a distinctly thorough user's manual—included with the new L2.1 Reference line-level preamplifier from Brooklyn's Lamm Industries, earlier products from which have impressed me as among the best available. Indeed, coming from almost anyone else, the above quote would strike me as trivial boasting—but I know from experience that…

Lamm Industries L2.1 Reference preamplifier Page 2

The L2.1 Reference is turned on with the Power switch on the front panel of its power supply; that switch flipped, a red LED next to it flashes steadily, indicating that the Lamm's various components are charging up, warming up, and altogether settling in. Just over 45 seconds later, a relay emits a soft click, the light glows steadily, and the L2.1 is ready to use. The exceptionally thorough manual suggests that the preamp sounds its best after 25–30 minutes of additional warmup—which my listening confirmed. During its time in my system, the L2.1's overall sound quality seemed to change…

Lamm Industries L2.1 Reference preamplifier Specifications

Sidebar 1: Specifications

Description: Solid-state line-level preamplifier with separate tubed power supply. Tube complement: one 12AX7/ECC83, one 6C19P, one 5651A, two 12AX3. Inputs: 4 single-ended (RCA). Outputs: 2 single-ended (RCA), 1 balanced (XLR). Input sensitivity: 0.135V RMS, ±2%. Input impedance: 50k ohms. Output impedance: typically 130 ohms. Frequency response: 20Hz–20kHz, ±0.2dB; 5Hz–120kHz, ±3dB. Slew rate: 30V/µs. Risetime: 1µs. THD: <0.03% at 2V RMS. Signal/noise: typically 94dB, 22Hz–22kHz, below 2V RMS output. Power consumption: 80W.
Dimensions: Preamp and power…

Lamm Industries L2.1 Reference preamplifier Associated Equipment

Sidebar 2: Associated Equipment

Analog Sources: Garrard 301 turntable; EMT 997 tonearm; EMT OFD 15 & TSD 15, Ortofon SPU #1S, Shindo Laboratory SPU pickup heads; Denon DL-103 cartridge.
Digital Sources: AudioQuest DragonFly Red, Halide Design DAC HD USB DACs; Apple iMac computer (late 2015) running OS 10.12.1 & Roon v.1.2, Build 165; Sony SCD-777ES SACD/CD player.
Preamplification: Auditorium 23 Hommage T1 & T2 step-up transformers; Sentec EQ11 phono preamplifier; Shindo Laboratory Masseto preamplifier.
Power Amplifier: Shindo Laboratory Haut-Brion.
…

Lamm Industries L2.1 Reference preamplifier Measurements

Sidebar 3: Measurements

I measured the Lamm L2.1 Reference preamplifier with my Audio Precision SYS2722 system (see the January 2008 As We See It"). All measurements were taken at the preamplifier's Direct inputs, which bypass the input switching. The gain with the volume control set to its maximum was 8.8dB, unbalanced input to unbalanced output; and, as expected, 6dB higher from unbalanced input to balanced output. The twin volume controls operated in accurate 1dB steps, and the unity-gain setting at the unbalanced outputs was with the controls set to 3:30. Both sets of outputs…

AnalogueWorks Zero turntable

My main task is to describe an audio component's basic character. How was it made? How did it fit into my system? How effectively did it deliver musical performances? My goal is to create stories that generate sounds and images in your mind—stories that will allow you to imagine how the component might perform in your system.

I can hear the moans from all you objectivist guys: Please, Herb, spare us your purple prose.

But guys! Our full appreciation of music, art, and perfectionist audio depends entirely on our ability to imagine. The most practical measure of any hi-fi…