Denon gives the consumer a reasonable amount of choice when it comes to the M51 2.1 Surround Sound system. You can either purchase just the base surround amplifier/reciever, and match it up to speakers and a subwoofer of your choice, or purchase essentially matching speakers and subwoofer to go along with it. Naturally, adding in speakers and a subwoofer does up the price a bit, and the configuration of the M51 we tested with included 2 Denon speakers and a Denon subwoofer.
The main amplifier/reciever of the M51's playback unit is a relatively small unit decked out in stark metallic tones. Basic functions can be accessed either from the front of the unit, or from the exceptionally well laid out remote. At first glance, the M51's remote is quite intimidating, with a huge array of buttons, but closer examination reveals a very sensible layout, with common buttons sitting at the base of the unit and having particular shapes that become second nature very quickly. To top it off, the common function buttons are made of mildly phosphorescent plastic, so it's easy to locate them in a darkened home theatre room.
The optional speakers comprise a intimidating subwoofer decked out in wood tones that should fit well with a variety of decor styles, along with two satellite speakers. The speakers share a mix of the wood motif of the subwoofer and the metallic style of the amplifier/reciever unit.
Setup of the M51 is simple enough, with cables that tightly screw down and a rather thick manual that's easy enough to follow. It's even been put together well enough that it covers all possible bases in terms of speaker seperate options that you might want to hook up to it.
In a world of 5.1, 6.1 and 7.1 speaker systems, a 2.1 layout might not sound terribly impressive, but to counter that the system comes with Dolby Digital Virtual Surround Sound, which simulates the effect of a true 5.1 surround sound system. If you're in a situation where even blasting out a simulated surround effect is likely to irritate your fellow housemates, you'll be glad to note that it also supports Dolby Headphone, which likewise simulates a 5.1 surround effect through headphones.
The amplifier itself can handle most common inputs and outputs, although it's worth noting that video output comes from a single SCART socket at the rear. SCART's common enough in the European market, but less so in Australia, and if you're keen on the M51, you'll need to pick up a SCART converter to go with it. Denon kindly provided us with one for testing purposes. In playback terms, the amplifier/receiver can handle standard DVD, DVD-R/RW, DVD+R/RW, Video CD, Audio CD/CD-R in MP3/WMA format and Kodak Picture CDs.
The M51's 2.1 speaker system has two main factors that could make it appealing. If you're stuck for space to properly lay out a 5.1 or greater speaker setup -- or simply don't want to have that many speakers affecting your home decor -- it's undoubtedly easier to just have to set up two speakers, the reciever and the subwoofer. With Virtual Surround sound, too, it's not quite so vital to fuss about correct speaker placement, as the surround effect is just an effect.
In our testing, the M51's surround effect worked better than we would have given it credit for. It's still going to be beaten by any 5.1 speaker setup of good quality, but if you've got cheap and cheerful speakers, the quality of the M51 will surprise you. Implementing surround sound is simple enough from either the remote or the receiver, and as you'd expect, the surround effect works better with some discs than others. Likewise, depending on the room you're going to set the M51 up in, the surround effect may be weaker or stronger. We set up the M51 in a small but somewhat crowded room, and predictably found that removing items that muffled the sound reverberations improved audio quality more than a touch.
The receiver's onscreen display is minimalistic, but that makes it quite easy to manage, meaning you won't have to dip into the manual every time you want to alter a setting. The remote, as mentioned, is rather busy, and some functions up towards the top can feel a little obscure, but the main function buttons are exceptionally well laid out and quickly become second nature to use.
The M51 is a well-built, high performance 2.1 virtual surround system that comes recommended to anyone looking for surround sound in a situation where 5.1 surround just isn't possible.