MA Audio - Exhibitionist

The M680i also includes a 50Hz bass boost rated to be 18dB/octave. We measured boost at 50Hz at 14dB/ octave. If you've read our reviews before, you know this is a good thing. If your system lacks good bass, don't look to bass boost for a fix. Rather, build a better subwoofer system.

Installing the M680i is a piece of cake thanks to terminals laid out on only one side of the amp. All that's really necessary is to connect the power and speaker wiring, plug in an RCA audio cable and set crossover filters. Since there are two 20a ATC fuses on board, you'll need to install a fuse of similar value where you connect to the battery. Power and ground terminals accept 8-gauge wire.

Set-up is also pretty simple. The range of input signal is just 100mV-1volt. Even with 5dB of gain overlap, we couldn't hit full volume on our test head unit (2.31 volts) without overloading the input, meaning that head units pushing more than two volts from the RCA outputs will quickly drive the amp to clipping. If you're considering the M680i, make sure to mate it with a head unit pumping LESS than two volts at full volume.

The amp measures 15.8(L) x 9.9(W) x 2.14(H) in. Its size, looks and cooling requirements make it an "open" application amp, meaning you'll want to display it in the trunk or inside the cabin in a visible spot. The owner's manual even breaks down helpful truths about trunk mounting and how hot a trunk can get.

The ManualThe owner's manual covers five different MA amplifiers in this series. It has clear, easily understandable diagrams for each of the terminals on the amplifier and also a clear diagram for each of the control functions (bass boost and crossover). In back are explicit descriptions on how to connect several possible systems. It is, with the exception of one portion, a well-assembled aide.

There is one section, however, that contains misguided information regarding gain settings. Instructions state that you should "never turn up the volume of the head unit more than two-thirds of maximum volume to adjust the level." This is incorrect. If the head unit has clean (unclipped) output up to max volume, this allows the gain position to be set lower. Lower gain makes the signal, rather than the amp, work hard. Less work means less heat.

With just one volt of signal as the maximum input, two-thirds of volume would be a fraction of a volt driving the input, which is a great way to get unwanted noise into a system. Always ask the head unit to do the work of driving signal into an amp, then be sure the amplifier can handle the input voltage.

The MA Audio M680i performs decently for a 100 watt-per-channel amp, produces only moderate heat while driving 4-ohm stereo or bridged loads, and comes with an added cosmetic benefit-the clear top-for show. Paired with an appropriate head unit, it's a package with performance and panache.