A few readers have asked me to back off on being uber technical and get back to writing more about sound and high end audio from a listener's perspective rather than a designer's and I'll definitely do that but I did want to finish up on our little series about DACS.
One thing to remember is that while most of us just want to use our equipment as black boxes and not really care what's inside, I think it's always good to have some level of understanding about their workings to help make buying decisions. After all, an informed buyer is usually better equipped to make a choice that will bring greater musical joy than one without any understanding at all.
The first choice a designer has to make when it comes to the output analog stage of a DAC concerns gain: how loud the output of the DAC needs to be. This is an interesting dilemma for a number of reasons and one of the primary ones concerns what I just wrote about: making smart choices when it comes to purchasing your audio equipment.
Loud sounds better than soft. Sorry, it's just human nature and those of us having been around long enough have watched the audition process too many times to ignore it. Most users will always pick the louder DAC than an identical sounding one with less gain. I have heard this described as sounding "more powerful" and "bigger" by those that don't gain match their audition pieces.
Secondly, the designer also has to determine use case: does the DAC have an internal volume control and if so is it likely to be used with or without a preamplifier? This is a tougher choice as an increasing number of DACS have built in volume controls.
If the user is going directly into a power amplifier, as we ask people to do with our PWD, then that unit must have enough gain to drive the amp without turning the DAC all the way up. Why? For two reasons: the first and most important is that you have enough volume to play all recordings at maximum level with any given amplifier. The second is the age old misconception that when a volume control is nearing the end of its range the sound can become "strained" as if it were a gas pedal on a car and taxing the engine. Like it or not, as designers, we have to give enough gain so people don't panic that they're running out "room" and straining the system - despite the fact they are not.
As I have written in past posts, this is completely wrong but the ideas remain for new users and older ones as well. Think of the volume control more like the car's brake, as opposed to its gas pedal.
Once the designer has figured out what gain they want, the next step is how will the output stage work and sound - in other words, what kind of configuration will it be? We'll cover some of that tomorrow.
The one thing you might want to take away from this article is the following: whenever you audition a new piece of gear, do your best to first gain match as closely as you can to whatever your reference is. Don't be fooled by a "louder is better" decision.