Adcom GDA-700 D/A processor System

Sidebar 1: System

For this review, I compared the Adcom GFA-700 with the EAD DSP-1000 and the Audio Alchemy DDE v3.0 HDCD decoder fed through its I2S bus by a DTI 2.0 digital jitter reduction unit. Both standard and HDCD-encoded CDs were played on a Krell turntable. For an overall collection of superbly recorded HDCD-encoded music, I used the HDCD Sampler Volume 2 (Reference RR-90CD), which includes classical, jazz, and a selection of three musical samples recorded with and without HDCD for comparison. A single 75 ohm digital-specific Silver Starlight coaxial cable was run from the turntable and directly plugged into the converter under test.

All converters were plugged into the AC mains for at least 72 hours before any listening. Each decoder under test drove a Bryston BP-25MC preamplifier whose balanced outputs drove the amplifiers through a Bag End ELF-1 Integrator electronic crossover set at a 90Hz high-pass frequency. Cogelco Yellow interconnects were run from the Krell to the ELF-1, with extra Cogelco pairs then run to the two power amplifiers. A Mark Levinson No.331 solid-state amplifier drove Quad ESL-63 USA Monitor electrostatics on Arcici stands via Sumiko OCOS speaker cables in bi-wired configuration. A Krell KSA-250 drove ELF S-18-1 subwoofers via Monster Cable. The Quad "satellite" loudspeakers were placed 4' from each side wall and 3' from the back. The ELF S-18-1s were placed in the corners of the room, behind and alongside the Quads.—Larry Greenhill

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tonykaz's picture

Ok, its an Adcom.

Bob Katz just revealed ( in his Innerfidelity Article ) how DACs are becoming "transparent".

His most recent DAC is even more transparent that his previous DAC, which he seemed to think of as perfectly transparent.

However, it seems to require a superb STAX headphone system ( acting as an Audio Microscope ) for even professional Sound people to hear these differences.

The important word of wisdom here: "transparent".

So, that's the quality we should be considering in DACs : they should be "clear windows".

Of course a person would need to know what the music "should" sound like. How is anyone supposed to be able to know this??

Tony in Michigan

Dakmart's picture

... Isn't HDCD actually owned by Microsoft these days?

John Atkinson's picture
Dakmart wrote:
Isn't HDCD actually owned by Microsoft these days?

Yes it is, since 2000, but they don't appear to have done anything substantive with it. See

John Atkinson
Editor, Stereophile

JRT's picture

This article about the old Adcom GDA-700 mentioned that it used Pacific Microsonics' PMD100. That PMD100 was a flawed design that audibly colored the sound. The design flaws were later corrected in the PMD200.

The PMD200 was Pacific Microsonics code running on an off the shelf DSP, and was not backward compatible with the flawed PMD100 which was a device specially manufactured for Pacific Microsonics.

Regardless any of that, for better HDCD playback than you will get from a device using the PMD100, dBpoweramp can be used to transcode HDCD data to 24_bit, 44.1_ksps PCM digital audio, and can convert that to suitable FLAC. You can play that back from a variety of devices and software through a modern DA converter without need for the now obsolete Pacific Microsonics DSP.