Description: Class-A sliding-bias monoblock power amplifier. Inputs: single-ended on XLR jack. Outputs: 2 pair binding posts. Power output: 250Wpc into 4 ohms (21dBW). Frequency response: 10Hz–100kHz, ±0.3dB. Sensitivity: 1.6V RMS for maximum output. Input impedance: 10k ohms. Voltage: AC 120V or 240V selectable, 50Hz or 60Hz. Standby power: 10W. Idle power: 28W.
Dimensions: 11" (270mm) W × 11" (270mm) H × 18.5" (490mm) D. Weight: 62lb (28kg).
Finish: Silver, gold, black, or any combination for body and heatsinks.
Serial numbers of units reviewed:…
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Sidebar 2: Specifications
Sidebar 3: Associated Equipment
Digital sources: dCS Vivaldi Apex DAC, Vivaldi Upsampler Plus, Vivaldi Master Clock; EMM Labs DV2 Integrated DAC, Meitner MA3 Integrated DAC; Innuos Statement NextGen Music Server; Uptone Audio EtherRegen, AfterDark Giesemann Emperor Double Crown Master Clock, and Nordost QNet Ethernet Switch, all powered by Nordost QSource linear power supplies (2); Synology 5-bay 1019+ NAS powered by Ferrum Hypsos linear/switching hybrid power supply; Small Green Computer Sonore Deluxe opticalModule, Linksys mesh router and Arris modem, all powered by HDPlex 300 linear…
Sidebar 4: Measurements
Logistical issues meant that I measured different samples of the Infigo Method 3, serial numbers 3022-0002 and 3022-0003, than those auditioned by JVS. I started the testing with sample '0003, using my Audio Precision SYS2722 system. Initially, I used a balanced connection between the Audio Precision's signal generator and the Method 3. I preconditioned the amplifier following the CEA's recommendation, operating it at one-eighth the maximum power into 8 ohms for 30 minutes prior to testing. At the end of that time, the right-hand heatsink was warm, at 101.8°F (38.8…
Manufacturer's Comment
Thanks to Jason and all at Stereophile for such a great review of our amplifier.
All Infigo Audio models are designed to create the ultimate musical experience. Of course, measurements are important, and we thank John Atkinson for uncovering some things that will lead to demonstrable improvements.
Scrutinizing the bias circuit to find and fix what caused those issues revealed a small undershoot of idle bias current right after the zero crossing of the signal. This undershoot deepens with increasing frequency and with total signal-current drawn. This…
The concept of streaming digital music files over distances great (as with internet-streaming services like Spotify, Qobuz, Tidal, etc.) and small (from a home-PC hard drive, NAS, or networked music server) became mainstream only recently. But it was already brewing during the late 20th century, with people illegally downloading low-bitrate MP3 files made from CD rips and coming close to killing the recorded-music industry.
That wasn't streaming exactly, or not in the current sense, because the files needed to be downloaded, stored locally, then either played out of a computer or loaded…
Headphone listening
The next thing I did was plug in some headphones. I wanted to learn if I could hear differences with the same tunes streamed over Qobuz via Bluetooth from the phone vs the desktop Qobuz app via USB, and vs Qobuz through Roon via Wi-Fi. I tried an assortment of music from Qobuz's new releases. The Bluetooth stream sounded a bit plastic, as Bluetooth will—not the same tonal balance and not as much low end as Qobuz streamed through Roon via Wi-Fi and direct from Qobuz on my computer connected by USB.
Between USB-connected Qobuz and Roon-streamed Qobuz,…
Sidebar 1: Specifications
Description: Streaming digital-to-analog converter with built-in Roon core and network-server capabilities, with analog preamplifier, headphone amplifier, and MM/MC phono stage. Digital inputs: Bluetooth 5, Wi-Fi, Ethernet, S/PDIF (2 RCA, TosLink), USB2 Type B, 2 USB-A (for attaching storage or another DAC for a second Roon zone). Analog/phono inputs: one pair single-ended (RCA) line-level, one pair single-ended (RCA) phono. Analog outputs: one pair balanced (XLR), one pair single-ended (RCA). Headphone outputs: two ¼" stereo convertible to 1 pair balanced; 6W…
Sidebar 2: Associated Equipment
Digital sources: Oppo DV-981HD universal disc player, dCS Bartók DAC/streamer.
Analog sources: Technics SL-1200MK7 turntable, Ortofon 2M Blue cartridge, Pro-Ject Phono Box RS2 preamp.
Preamplifier: Benchmark LA4.
Power amplifier: LSA Warp 1, Little Labs Monotor (headphone).
Integrated amplifier: McIntosh MA6500.
Loudspeakers: B&W 808, Amphion One18.
Headphones: Sennheiser HD 650, Neumann NDH 30, AKG K240DF.—Tom Fine
Sidebar 3: Measurements
I measured Mytek's Brooklyn Bridge II Roon Core using my Audio Precision SYS2722 system. I powered up the Mytek then connected it to my router with an Ethernet cable. However, the processor remained inert—it needed to be powered up after the Ethernet connection had been made. When I opened the Roon 2.0 app on my iPad mini, Roon identified two Brooklyn Bridge IIs in the Audio Settings window, one a generic ALSA device, the other a networked audio device not yet certified. I managed to enable the latter.
The Brooklyn Bridge II was recognized as a Roon core. I…
The standup bass genius and jazz force of nature Charles Mingus made his first album for Atlantic Records, Pithecanthropus Erectus, in 1956. Several of his most memorable musical masterpieces, including The Clown (1957), Blues and Roots (1960), and Oh Yeah (1962), followed as he intermittently returned to the label throughout the 1960s and early '70s. Beginning in 1974 with Mingus Moves, the cigarillo-chomping, famously gruff Mingus recorded most of his final albums for the label as he progressed from composer/player to wheelchair-bound writer and musical director. His final seven studio…