Surround Controller
Specially designed for surround sound, there really isn’t any alternative if you take surround sound seriously. Uniformly controlling the volume of all channels is not a simple matter and requires specialized and high quality equipment.
Active and Passive Monitor Controllers
Monitor controllers should only manage the sound, not produce their own. If you place a lot of value on an absolutely pure output then you should consider purchasing a controller which is made primarily with passive components. For some only the signal path is passive but there are others which don’t require a power supply at all. These purely passive controllers are limited in their functions however as not much can be done with them besides volume control, mono switching and speaker selection. More complex and versatile are controllers which use some active electronics like internal capacitors (IC’s), transistors, LEDs etc. By using relays and passive volume controls they can keep the signal path passive and as distortion free as possible.
Mini-Mixers
Are they a suitable alternative to their full size counterparts? Maybe. Some of the ‘classic’ features of a monitor controller are also included in mini-mixers e.g. volume control, headphone amplifier, and mute. Occasionally you can also find a mono switch. Unfortunately, a switchover between different pairs of speakers, like the mono switch, is an essential feature in today's studio environment. Another negative for the mini-mixer is that, for cheaper devices, the volume control is almost always permanently in the signal path and compromises the sound even in a neutral setting. This is ok when they are being used for their intended purpose but for more professional or critical studio projects you should invest in a complete monitor controller though.
At the end of the day mini-mixers are an affordable alternative to, but not complete replacement for, monitor controllers in today’s studio environment. Even if a monitoring controller does not open up new sound possibilities, like a channel strip or new synthesizer would, it does improve the work environment and with that the final sound quality.
Its relatively straightforward to manufacture a passive controller with just a volume pot, but features such as mono switches and headphone amps need active circuitry. As with anything, to a certain degree you get what you pay for, and good quality active circuitry tends to come at a cost, so its sometimes better to opt for a passive rather than active controller if youre on a restricted budget, as you will generally get better audio quality for a given price. As an alternative, some designs maintain a passive path for the main signal, but use active circuitry for a headphone amp. If you want anything but the most basic features though, youll have to go for an active design, but remember that every switch and potentiometer colours the signal to some extent, so unless you can afford the very best quality, you might want to choose something that has just what you consider to be essential, rather than go for the model with the longest spec list.
The control surface is an invaluable piece of equipment found in numerous project and large-scale studios, offering control of various parameters of your DAW software. So why not just use one to act as your monitor controller? One reason is that as the control surface is only controlling your software and not the audio directly, it will not be possible to use it to rectify any horrible digital noises caused by crashes or freezes of your DAW - no amount of knob twiddling will protect your speakers from digital meltdown! Of course there are also more obvious benefits to the monitor controller which are not available on the control surface such as accommodating multiple audio inputs from CD players and master recorders, and also many of the other features mentioned earlier in this guide. Having said all this, some high-end hybrid controllers are now starting to appear with analogue monitoring sections built in.
A regular small mixer will be adequate for some set-ups, and features such as mic pre-amps and EQ can be useful additions, but using a mixer in this manner adds unnecessary length to the monitoring chain, and can colour the signal as it is routed through EQ and gain controls - leaving an EQ section flat does not mean that the signal is unaffected. If youve used the same mixer for a number of years, its possible to be aware of the effect that your mixer has on the sound and to compensate for it. This is not ideal, but can work if youre on a tight budget, although of course most small mixers will not offer the kind of feature set found on even an averagely specified monitor controller.