Studio monitor loudspeakers with digital inputs – whatever will they think of next? The question is bound to be whether 'digital' loudspeakers are practical, useful, or indeed the way of the future?
First, let's be clear that the only thing that is digital about these studio monitor loudspeakers is the input. Within centimeters of the input socket, the signal is transformed back into good old analog. Maybe one day there will be a monitor loudspeaker with a digitally controlled diaphragm. But I suspect that day is some way off.
Since the current crop of Roland digital monitors, such as the Roland DS-90A, also have analog inputs, precisely what is the advantage of going digital?
OK, first off – one big advantage is that these are active monitors, meaning that they have power amplifiers inside. You don't need an external power amplifier. For me, this has always been the way to go. For one thing, the characteristics of the amplifier can be precisely tuned to the requirements of the drive units. For another, there is no signal loss in the cables, which although it is almost imperceptible in terms of level, it definitely creates audible frequency response anomalies. To my mind, the only loudspeakers that should not be active are those that are meant to be flown in large-scale PA systems – not much point flying all that extra weight!
But the digital inputs? Well one disadvantage is that if you use the S/PDIF input, then the maximum cable run is about 25 feet (8 meters). If you intend on a proper cable installation in trunking or conduit you could easily exceed this. If you prefer the optical connector, then I have seen cables up to 30 meters (100 feet), but the cost seems disproportionate. A standard line level analog signal in comparison will travel pretty much as far as you like without audible degradation. Now, if these speakers had AES/EBU digital inputs, then things would be different, but alas no.
Where digital monitors could really score however is in having a digital, rather than analog, crossover. The separation of frequency bands between the drive units has always been a tough task for passive monitors. It is a lot more practical in active monitors since the crossover operates on a signal that is much lower in level. The circuit design can be optimized to the requirements of the drive units. However, if the crossover is digital, then potentially every little defect in the drive units' response can be corrected. There is practically no limit to how complex a digital crossover can be, while maintaining excellent sound quality. It would be nice if Roland could be a little more specific about this because nowhere in their product literature do they say that the crossovers are digital. I suspect they are not.
So my conclusion is that the digital input, at last in this range of monitors, is a bit of a red herring. I can see a day when we might for instance use networked studio monitors, but that's another thing entirely. As for being active, well that's great. And digital crossovers? Could be the way of the future…
If you buy the Roland DS-90A studio monitors, or similar, then it will be for their sound quality. The digital inputs are irrelevant.