here's Hi-Fi Choice review on the Marantz PM7200 KI
Given the way we (and plenty of you, evidently) reacted to the basic, non-signature, PM7200, why on earth would Marantz want to upgrade it? Let's see: we accused it of having "bags of power... remarkable refinement... bass goes down for miles...". Okay, you get the idea. But we also pointed out that, bargain though it may be, it's not part of the real high-end pantheon.
So has Ken Ishiwata's signature on the front changed that? What, in fact, has he changed apart from the badge? Most obvious is the chassis, now entirely copper-plated inside and out. It's pretty and it's also functional, improving the conductivity of the metalwork and hence making it more effective at keeping interference out. Internally there are some component changes and a new toroidal mains transformer, entirely wrapped in copper foil to reduce electrostatic interference. Keeping with the theme, power transistors are also now covered with a copper-plated shield, and some internal wiring has been changed from stranded to solid core.
The biggest practical difference all these changes seem to make is to reduce the output power. Continuous output is just a little under 100 watts and peak output is around 110 watts, the former less than 1dB below the standard amp but the latter more like 2dB down. Put in those terms, it's not a big problem, and frankly you're still looking at a pretty powerful lump: it's also a little more assured into lower impedances so there is a quid pro quo. What may prove to be an issue is that hum is slightly increased compared with the standard model, at least on the review sample. This is almost certainly due to magnetic interference from the new transformer - copper foil doesn't do much about that, unfortunately. It's a buzzy,
high-frequency sort of hum on the left channel and with sensitive speakers it may just become audible at typical listening distances: however, the way toroidal transformers are made is inherently slightly inconsistent and levels of hum may vary between units.
In case you missed the original PM7200 review, here's a quick recap. This is an integrated amp with a fairly typical set of features - bypassable tone and balance controls, twin speaker outputs, plenty of inputs including phono and a remote control. But it also has unusually high power around the 100-watts mark plus the distinguishing feature of a choice of operating modes - high power Class AB or medium power (around 30 watts) Class A. In both original and KI units, Class A holds up to ten watts or a little under, so strictly speaking it's really highly enhanced Class AB. You can switch between the modes on the fly, which makes for fascinating comparisons, though in practice, at power levels within the Class A envelope, both we and at least one HFC correspondent found that differences are often so small as to make one wonder whether anything has changed.
Apart from the KI changes, construction is good inside and out but the casework is prone to resonance and a little damping wouldn't go amiss. This is easy for the user to experiment with of course, but if you're going to use Class A mode don't block up the ventilation slots! There's quite a lot of heat to get rid of and watching your hi-fi catch fire can seriously spoil a listening session...
SOUND QUALITY
It's been a while since the basic 7200 left HFC but luckily one such unit (not the one we reviewed) was also on hand for part of the listening tests, which reduced reliance on memory. At least one recollection proved correct: it's a very capable amp. Probably the toughest test of any true audiophile amp - high-power ones, anyway - is the extent to which it can fully take charge of any given speaker and show it who's the boss. That's also the area where budget amps have come on most obviously over the past decade or so, and while the 7200 isn't going to displace many Krells from their owners' affections it shows a lot more aptitude in that area than previous sub-£500 amps. Give it some high-energy programme in any musical genre and it will keep a tighter rein, with correspondingly tauter definition especially across the bottom couple of octaves, than one might expect from it.
It's probably in that department where the KI shows the most marked improvement over the basic 7200. And it's an interesting comparison too, not quite as simple as just being tauter or more extended. In fact it sometimes sounds less extended but that's not the actual case. What is actually happening, as becomes much clearer on extended listening and comparison with high-end references, is that the limits of the non-KI are being reached with some very tough basslines and its grip is relaxing just sufficiently to allow just a little bass bloat.
The KI, on the other hand, is less easily rattled and holds on just that little bit longer, keeping the sound together and under better control, with less immediate impact but noticeably more detail and definition. There's also no feeling that the sound is being restricted in any way, and perhaps the best way to describe the overall effect is that the KI sounds somehow smoother in the way it handles the bass. For an intuitive analogy of sorts, think of two stones of equal size, a rough piece of sandstone and a polished piece of granite. Despite its sophisticated finish, the granite clearly is the tougher and harder - and frankly more interesting - of the two. The KI feels a little like that.
Pseudo-poetic bass apart, what of higher frequencies? The difference seems less marked here. The midrange of both amps is very detailed, highly neutral and very well defined spatially, leading to excellent stereo imaging. Just occasionally, listeners felt that the basic amp had the edge in image specificity over the KI, but if there was a difference it was so small as to be barely repeatable. The KI did seem to offer slightly more depth though, in most cases. As for the treble, again the KI had a slight advantage in cleanliness, though in a couple of tracks the basic appeared to be slightly ahead on extension and 'air'.
And as we found the first time round, switching from Class A to Class AB mode can often be a complete non-event. Obviously if you drive the amp flat out in Class AB and switch to Class A the resulting distortion will be blindingly obvious and very horrible, but short of extreme cases like that there's very little to hear. Maybe, just maybe, Class A is a little sweeter and more clearly defined tonally with well-recorded acoustic material, but then Class AB seems more detailed in quiet passages. Experiment by all means - it can't do any harm and however you look at things you'll be in little doubt that you're listening to a very fine amp.
So to the crunch: does the 50 per cent price hike justify itself? It's hard to say. If the 7200 didn't exist we'd recommend the 7200 KI at £500 like a shot anyway. Probably the fairest way to deal with this is to say that the law of diminishing returns very slightly favours the basic model, but the KI is a damn fine £500 amp in its own right. If you can afford the difference, audition it, but if you can't, then don't bother gnashing your teeth over it. It is, after all, just a matter of taste.
Build - 4 stars
Sound - 4 stars
Value - 4 stars
Overall - 4 stars
