Onkyo INTEGRA A-701XD (1988)

At 17kg, it lands on the rack like a declaration: this is not your average integrated amp.

Overview

The Onkyo INTEGRA A-701XD isn't a subtle machine. Released in October 1988, it was built as a pre-main amplifier derived from the higher-end Integra A-817XD, but with a crucial addition: a built-in D/A converter. Priced at ¥99,800 at launch, it targeted audiophiles who wanted digital capability without stacking separate components. What sets it apart isn't just the specs—it's the obsessive engineering language Onkyo used to describe it. This wasn't just another box in the rack; it was a statement of intent, packed with proprietary tech that sounds almost alchemical on paper.

Its 17kg weight gives the first clue: this is a chassis built like a vault. The bottom plate is 2mm thick steel—twice the norm at the time—and the entire internal layout follows a 2-box structure, isolating the power supply from the signal circuitry. Even the heat sink is engineered for sonic isolation: a U-shaped design that forms a closed loop, cutting electromagnetic coupling while using asymmetric fin lengths (14mm and 18mm) to disrupt resonance. These aren't cost-no-object luxuries; they're deliberate choices baked into a machine meant to reject noise, vibration, and interference at every level.

It’s also a snapshot of late-80s digital ambition. With support for 32kHz, 44.1kHz, and 48kHz sampling rates, an 18-bit "super-real" D/A converter (one per channel), and an 8-times oversampling digital filter, the A-701XD was designed to future-proof analog lovers against the CD revolution. The DAC section is shielded in its own case, outputs a clean 2V signal at 0dB, and achieves a remarkable 0.0015% THD at 1kHz. But Onkyo didn’t stop there—they added a DAC direct switch, letting users bypass the analog low-pass filter entirely. Whether that improves sound or simply offers experimentation is up to the listener, but the option itself speaks volumes about the era’s fascination with signal purity.

On the analog side, it’s equally serious. The phono stage handles both MM (2.5mV/47kΩ) and MC (160μV/220Ω) cartridges with exceptional linearity—RIAA deviation is held to ±0.2dB—and distortion figures are microscopic: 0.003% for MM, 0.015% for MC. Signal-to-noise ratios back this up: 94dB for MM, 75dB for MC (measured at 5mV and 0.5mV inputs respectively), and a stellar 110dB for the D/A stage. The tone controls are no afterthought either: ±8dB at 20kHz for treble, ±10dB at 20Hz for bass, and a dedicated contrabass boost (+10dB at 20Hz), all adjustable with volume set at -16dB. It’s a feature set that assumes the user will tweak, not just listen.

Specifications

Key Features

18-Bit Dual-Mono D/A Converter with Shielded Enclosure

The A-701XD’s digital heart is a pair of 18-bit "super-real" D/A converters, one for each channel, operating in true dual-mono fashion. This wasn’t common in integrated units at the time, where cost-cutting often meant shared DACs or lower bit depths. The converters are fed by an 8-times oversampling digital filter, reducing aliasing and smoothing the reconstruction process. To protect the delicate analog output stage, the entire DAC section is enclosed in a dedicated shield case—a physical barrier against noise from the power supply and amplifier stages. The result is a measured dynamic range of 103dB and a THD of just 0.0015% at 1kHz, with a full-scale output of 2V. These numbers weren’t just competitive—they were elite for a 1988 integrated design.

DAC Direct Switch for Filter Bypass

Onkyo included a dedicated DAC direct switch that allows the user to bypass the analog low-pass filter entirely. This feature reflects a philosophy that was gaining traction in high-end audio: that some listeners might prefer the raw, unfiltered output of the DAC, even if it includes ultrasonic artifacts. Whether this improves sound or simply offers a different flavor is subjective, but the inclusion of the switch shows Onkyo trusted users to make their own decisions.

Optical Drive Amplifier with Photovoltaic Element

At the first stage of the power amplifier section, Onkyo implemented a "newly developed optical drive amplifier" that uses a photovoltaic element in the differential amplifier circuit.

2mm Steel Bottom Chassis with Double-Structure Insulators

The chassis isn’t just heavy—it’s overbuilt. The bottom plate is 2mm thick steel, double the thickness of conventional designs, providing a rigid foundation that resists microphony and vibration. The legs use a double-structure insulator combining copper plate and cork material, a hybrid approach meant to decouple the unit from the shelf while maintaining electrical grounding. This attention to mechanical isolation extends to the internal layout: the power supply and circuit sections are separated in a 2-box structure, and the voltage amplification and power stages are further partitioned. It’s a top-to-bottom commitment to signal integrity.

Source Direct Switch for Pure Signal Path

For users who want to strip away tone controls and buffers, the A-701XD includes a source direct switch. When engaged, all input sources are routed directly to the power amplifier via a dedicated volume control, bypassing the preamp’s tone and balance circuits. This isn’t just a mute or bypass—it’s a complete reconfiguration of the signal path, designed to deliver the cleanest possible sound. Combined with the DAC direct switch, it gives the owner multiple ways to tailor the signal chain to their preference.

Gold-Plated CD Input and Vise-Type Speaker Terminals

Input quality is taken seriously: the CD input uses a gold-plated pin jack, a nod to the importance of preserving digital and analog signals at the entry point. The speaker terminals are large vise-type connectors, capable of accepting bare wire, spades, or banana plugs, and designed for high-current delivery. These aren’t just cosmetic upgrades—they reflect the amp’s high current output (up to 295W into 2Ω) and the need for robust, low-resistance connections.

Collectibility & Value

Current market listings show prices ranging from $777.00 to PHP7,999.00 (approximately $140 USD), with one seller listing it at "OUR PRICE : 18K" (likely Philippine Pesos, or ~$325 USD). This wide spread suggests condition, location, and working order heavily influence value. No detailed information is available on common failures or maintenance, though given its age and complex circuitry—including optical drive components and high-capacity Chemi-Con capacitors—owners should expect eventual servicing. The lack of spare parts documentation means repairs may require component-level expertise.

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