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Turntable: VPI HW-19 Mk.II fitted with the Well-Tempered Arm and Ortofon X-5MC cartridge; CD player: Musical Concepts modified Magnavox 1040; Power amplifiers: Belles Model One, plus a 180Wpc amp of my own construction; Speakers: Legacy-1; Interconnects: Mogami Neglex; Speaker cable: LiveWire BC-4. The Spatial Coherence was auditioned alone and in a side-by-side comparison with a Harman/Kardon Citation 21.

Source material used: LPs: The Scott Hamilton Quintet in Concert (Concord Jazz CJ-233); The King James Version, Harry James and his Big Band (…

Description: Full-function solid-state preamplifier with two phono inputs, three line-level inputs, two tape loops with selectable two-way dubbing. Original published specifications: Frequency response: 10Hz–40kHz +0, –0.5dB. Max output: 10V. THD: 0.05%. IMD: 0.05%. Phono S/N ratio: 80dB. Measured performance (footnote 1): RIAA accuracy: R channel, –0.25dB at 20Hz, –0.75dB at 20kHz (net: ±1dB); L channel, –0.25dB at 20Hz, –0.25dB at 20kHz (net: ±0.5dB). Line level frequency response: R channel, 20Hz–30kHz, +0dB, –0.1dB; L channel, 20Hz–30kHz, +0.5dB, –0.1dB.…

Looking out that desk window, I notice also the spring-warmed radiance of the sun, the racing shadows of ravenous sparrows, and daffodils. Each one of those things, in its way, affects…

But that is okay. Form must follow function.

At 42 ohms and 87dB/mW, the HEDDphone is easier to drive than the 83.5dB/mW HiFiMan HE6se and about the same difficulty as the 47 ohm, 88dB/mW Abyss AB-1266 TCs, which means it still requires extra gain and current to sound its best.

I…

Spectral's low profile is of their own choosing. They advertise very little, their products are demonstrated in a small number of stores, they almost never send products to magazines for review, and they are very quiet about their accomplishments. Rather than push their products on customers, they seem to let a small segment of the market…

The analog output stage is based on the circuits Keith Johnson has been refining for more than 20 years. The SDR-2000 Pro's output stage is very similar to the electronics used throughout the signal path in Keith's recording electronics, which are used to make all the Reference Recordings releases. The circuit features a differential JFET input stage and a MOSFET cascode, followed by a differential cascode voltage-gain stage. High-current power…

RH salivated over the Spectral SDR-2000 Professional HDCD D/A processor in Vol.18 No.5, and this was my first chance to hear it in my system. He did not exaggerate. It is clearly a Class A processor; it may even be the best processor in Class A, though I haven't had the opportunity to compare it directly with the Mark Levinson No.30.5, which isn't exactly chopped liver (footnote 1).

At first I found the differences between the SDR-2000 and the Mark Levinson No.36 D/A converter to be subtle—less notable…

Description: Digital Processor with HDCD decoding. Inputs: three coaxial on RCA jacks, two AES/EBU on XLRs, TosLink optical, Spectralink. Controls: digital input select, polarity inversion, mute, display dim, operate/standby. Sampling rates supported: 44.1kHz, 48kHz. D/A conversion: four custom 20-bit DACs in balanced configuration. Digital filter: Pacific Microsonics PMD100 8x-oversampling. Analog filter: passive, linear phase to 22kHz. Frequency response: DC–22kHz ±3dB (limited by encoding). DAC step resolution: 5µV or less. Digital noise output: 100µV p-p or…

I listened to the SDR-2000 Pro at the front of my usual reference system, and with an all-Spectral playback system with MIT loudspeaker cables and interconnects. The people at Spectral believe that their electronics and MIT cables are needed to fully hear the SDR-2000 Pro's musical performance. Although I agreed to replace my usual amplification and cables for part of this review, auditioning the SDR-2000 Pro in my familiar reference system was mandatory.

My system consisted of a Mark Levinson No.31 CD transport feeding the SDR-2000 Pro via…

The SDR-2000 Pro's maximum output level was lower than that of most processors, measuring just 2.06V from the balanced outputs and 1.03V from the single-ended outputs. These low levels are a result of the 6dB attenuation in the SDR-2000 Pro's analog stage to conform to the HDCD requirement. When playing HDCD-encoded discs, the maximum levels will be 6dB higher: 4.12V from the balanced outputs, 2.06V from the single-ended outputs.

The output impedance measured 200 ohms from the unbalanced jacks, 400 ohms from the balanced outputs at any audio frequency. DC…