Even our hardened delivery driver made comments about the weight of the Marantz SM-11S1 power amp and we rather cynically expected heavyweight casework to be the culprit.

In fact, the main contributing factor is one of the biggest transformer enclosures we've seen - there's a screening can (with inaccessible fixing screws) over something that's probably big enough to weld with!

Imposing amps

Yes, the base of the amp has been beefed up so it doesn't warp due to the loading of that transformer, but the rest looks pretty sane. There's plenty of power supply capacitance in evidence and the heatsinks really mean business.

All the same, these are both very imposing bits of kit and we mean that in a positive way. The bulk is offset by subtle curves and recesses which break up the otherwise daunting frontal area.

Clever components

Each unit has a little digital meter centre stage, reading gain in the case of the preamp and output power (for each channel) on the power amp.

The latter is rather clever, actually, since it monitors both voltage and current to give a real reading which we found both accurate and quick to respond - this could settle some burning arguments in the hi-fi world!

Marantz also offers a phono stage and it's no afterthought. The relevant circuit board is quite large and densely packed and handles both flavours of cartridge. Apart from that, there are five unbalanced line inputs and two balanced, plus two recording outputs and balanced/unbalanced outputs.

The power amp has inputs of both flavours and two switched sets of speaker terminals.

Weighty bass

Such criticisms, as were made of these amps, seemed mostly in regard to the treble, which was felt as being a little closed-in and lacking air. There were also a couple of comments on restricted stereo image depth, but it's a fair bet that's a related issue.

Bass, however, was felt to be very satisfying, with real extension and weight, but also plenty of control so that low instruments never seemed vague or woofy. Midrange is well integrated with the rest and shows no obvious signs of coloration.

The treble restriction gives the sound its own character, which is by no means unpleasant. Plenty of recent recordings have a very busy top end and a slightly mellower presentation
is no bad thing.

It's mostly with already mellow recordings, especially those made with natural miking techniques, that the sound may be found a little lacking. When treble energy is less overt, it needs very careful handling if it is not to lose its delicacy and those subtle cues that tell the listener so much about the recorded acoustic.

With such recordings, the space seems to close in a touch and instruments lose a little of their own character.

Subtle performance

When music is lively and energetic, though, these amps are a lot of fun. Indeed, the timing in the bass was felt to be among the best and the 'party potential' is not in any doubt.

Piano benefits from this with a particularly strong and fluid sound in the lower midrange, while the overall size of the instrument is made very clear. In terms of analytical listening, detail is good but not excellent.

One can hear everything that's going on, but it does require a little explicit concentration, where some amps make it effortlessly obvious.