Onkyo INTEGRA A-701XD (1988)

At 17kg, it lands on the rack hard. This is not your average integrated amp.

Overview

The Onkyo INTEGRA A-701XD is not a subtle machine. Released in October 1988, it was a pre-main amplifier derived from the higher-end Integra A-817XD, with one big addition: a built-in D/A converter. It cost ¥99,800 at launch and targeted audiophiles who wanted digital capability without stacking separate components. Onkyo described it in obsessive engineering language, and it was packed with proprietary tech that sounds almost alchemical on paper.

The 17kg weight is the first clue. The bottom plate is 2mm thick steel, twice the norm at the time, and the internal layout follows a 2-box structure that isolates the power supply from the signal circuitry. Even the heat sink is built for sonic isolation. It is a U-shaped design that forms a closed loop to cut electromagnetic coupling, and it uses asymmetric fin lengths (14mm and 18mm) to disrupt resonance. All of it aims to reject noise, vibration, and interference.

It is also a snapshot of late-80s digital ambition. It supports 32kHz, 44.1kHz, and 48kHz sampling rates, and has 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 reaches 0.0015% THD at 1kHz. Onkyo also added a DAC direct switch, which lets users bypass the analog low-pass filter entirely. Whether that improves the sound or just offers something to experiment with is up to the listener.

The analog side is equally serious. The phono stage handles both MM (2.5mV/47kΩ) and MC (160μV/220Ω) cartridges, with RIAA deviation held to ±0.2dB. Distortion is 0.003% for MM and 0.015% for MC. Signal-to-noise ratios are 94dB for MM and 75dB for MC (measured at 5mV and 0.5mV inputs respectively), and 110dB for the D/A stage. The tone controls give ±8dB at 20kHz for treble and ±10dB at 20Hz for bass, plus a dedicated contrabass boost (+10dB at 20Hz), all adjustable with volume set at -16dB. The feature set 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 section is a pair of 18-bit "super-real" D/A converters, one for each channel, running in true dual-mono fashion. This was not 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, which reduces aliasing and smooths the reconstruction process. To protect the delicate analog output stage, the entire DAC section sits in a dedicated shield case, a physical barrier against noise from the power supply and amplifier stages. Measured dynamic range is 103dB, THD is 0.0015% at 1kHz, and full-scale output is 2V. Those numbers were elite for a 1988 integrated design.

DAC Direct Switch for Filter Bypass

Onkyo included a dedicated DAC direct switch that lets the user bypass the analog low-pass filter entirely. The idea was gaining traction in high-end audio: some listeners might prefer the raw, unfiltered output of the DAC, even with ultrasonic artifacts included. Whether that sounds better or just different is subjective. The switch leaves the decision to the user.

Optical Drive Amplifier with Photovoltaic Element

At the first stage of the power amplifier section, Onkyo used 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 is heavy and overbuilt. The bottom plate is 2mm thick steel, double the thickness of conventional designs, which gives a rigid foundation that resists microphony and vibration. The legs use a double-structure insulator combining copper plate and cork material, a hybrid meant to decouple the unit from the shelf while keeping electrical grounding. The internal layout follows the same idea: the power supply and circuit sections are separated in a 2-box structure, and the voltage amplification and power stages are partitioned further.

Source Direct Switch for Pure Signal Path

For users who want to strip away tone controls and buffers, the A-701XD has a source direct switch. When engaged, all input sources go directly to the power amplifier via a dedicated volume control, bypassing the preamp's tone and balance circuits. It is more than a mute or bypass. It reconfigures the signal path for the cleanest possible sound. Combined with the DAC direct switch, it gives the owner several ways to tailor the signal chain.

Gold-Plated CD Input and Vise-Type Speaker Terminals

The CD input uses a gold-plated pin jack. The speaker terminals are large vise-type connectors that accept bare wire, spades, or banana plugs, and they are designed for high-current delivery. That fits the amp's high current output (up to 295W into 2Ω) and its need for 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). That 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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