We were enthused over Marantz's amplifier, the PM7001. So the ‘KI Signature' version ought to make it one of the year's hottest amps. ‘KI', of course, is Ken Ishiwata, ‘brand ambassador' for Marantz and an infectiously enthusiastic individual whose input guides the basic design of many Marantz products. He also applies further audiophile-type tweaks for the special edition versions that will bear his moniker.

In this case, those tweaks cover a wide range. Most obvious to the user is the addition of copper-plating to the case (inside and out) and gold-plating to the phono sockets, the former to improve interference rejection and the latter to enhance conductivity and reliability of the connections. Inside, while the basic amplifying circuit is essentially unchanged, the mains transformer has been swapped for a toroidal type with a substantial screening band round it. Also, individual copper-plated screens have been attached to significant transistors and diodes, and the main power-supply capacitors have been upgraded both in value and

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Various other components have been changed too, parts with the same basic values but higher performance in other ways. This may sound a bit ‘snake-oily' but there is a body of evidence that suggests not all capacitors of X value and Y working voltage give exactly the same performance in every way – one may be more stable than another, or give lower distortion, or have lower stray inductance and so on. That doesn't automatically mean they will sound different, but hey, they might...

Finally, the phono board has been substantially altered with an improved circuit of all-round higher performance. And just to recap the outline specification: 70/88 watts (its claim/our measurement) per channel, phono plus five line-level inputs, separable pre and power amplifier sections, twin speaker outputs and, by our measurements, stunningly good lab performance which falls just slightly short of the basic PM7001.

SOUND QUALITY

The general performance of the KI is clearly in the same ballpark as regards musical energy, detail and neutrality – in short, damn fine.

Our very few reservations regarding the PM7001 included a slight lack of authority in its handling of bass. Mr Ishiwata has been able to wring a touch more class out of the 7001 circuit, for the KI has more bass grip and came close in its degree of control to some quite expensive amps we tried.

We were also particularly impressed by the way it can simultaneously control bass and do the subtlest things with the treble. Music doesn't so often demand this, luckily, for not that many amps can really bring this off, but the 7001KI showed itself particularly adept in preserving delicacies like the decay of small percussion instruments while there's lots going on in the bottom octaves.

We continue to rate the excellent stereo imaging and clean, open and silky treble, both uncolored (barring some slight chestiness that was also present in the original 7001) and full of detail and insight, and the general way in which the amp can grab the listener's attention and hold it without discomfort for long periods. The phono input is clearer, too.

That Ken Ishiwata knows his stuff!

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Marantz PM7001 KI ¦ $1799 ¦  ¦ www.qualifi.com.au
For: Superb bass extension and control.
Against: Slightly noisier & mechanical than the plain 7001.
Verdict: Adds a little more refinement and better bass than the original.