Opinion: How Do I Pick The Parts of an Audio System?
Article writing/editing in-progress...
When I first started using portable headphones (before finding Head-Fi), I used to think that all I needed was a headphone that sounded great right out of my iPod. That was it. I'd heard about amplifiers (had not heard about DACs), but I thought "These headphones I read about on Macworld magazine already can get too loud to listen to with my iPod... Why would I want something to make music even louder?" Flash forward to now – where I've got over 15 things with built-in or separate DSPs, DACs, and amps – and I have a decent handle on how all the gear upstream of a headphone can affect the sound and unlock far more potential of a headphone than just make it louder.
Here's how I'll break it down:
What is it (definition)?
What stage of audio reproduction is it used?
What effect would an upgrade to this component have?
At what point is something not worth listening to and at what point have you reached diminishing returns?
Closing opinions.
Pretty straight-forward. I haven't listened to nearly everything, so this will be mainly opinions based on the perspective of gaming-suitable (with music/movies on the side) which will hopefully guide your thinking as you read Head-Fi gear reviews.
Source/File
Ok, I'm stretching my breakdown categories a little bit, but this is where I/we should start. I'm talking about MP3 files here, FLAC, movie files, the audio resources in a game.
This is the beginning of the audio chain, the recordings and samples that contain the sound info for reproduction. These days, it's usually digital unless you're using a vinyl record or a cassette tape, in which case the next step of the audio chain skips straight to the amplifier. Analogue sounds are expressed in chart-form by waves curving up and down and up and down, sine waves from school if you remember. Digital tries to recreate these wave shapes with something like a bar graph: at this moment the bar is this tall, next moment the bar graph would be a bit taller representing the wave going up, next bar a bit smaller, next bar smaller again, next bar a bit taller, and so on.
Upgrading this with more bars closer together equalling more accuracy to the original analog and a file with a higher sampling rate, and finer steps the bars can be measured in equals a truer tone to the original analogue tone and higher bit-depth. At the end of the day, digital is always going to look like stair-steps instead of a smooth analogue line, but with high enough sampling rates and bit depth it can seem smooth like a curve illustrated on a high-def computer monitor.
I'm pretty happy with 320kbps MP3s or 256 AAC, but I prefer 16/44.1kHz (that's bit-depth/sample-rate) CD quality or similar FLAC/Lossless quality when I can get it. I don't hear much difference beyond that, the biggest difference once you reach "lossless" and higher is how well a song is recorded or mastered. Anyhow, the audio source quality in games is usually compressed less than CD-quality anyway, so that will bottleneck the realism for gear down the line anyway.
DSP
Digital Signal Processor, something that processes the surround sound into a stereo mix for headphones that still sounds like it comes from surround directions. It can also do EQ, volume range compression, encoding and decoding sound channel mixes like Dolby and DTS, and other effects.
This effect has to happen while the signal is digital, so this comes before a DAC. DSP processing can be done with software running on your computer or in an external sound card-esq device, which may also have a DAC and amp built-in.
A system doesn't need to have a DSP to just make stereo sound, but it's really handy for gamers. So, the first upgrade is just having a DSP
Modern gaming consoles actually have a DSP built-in to take all the live gaming sound info, separate positional info to 5.1 or 7.1 channels for different speakers in a home theater, and finally compress that data so it can be sent over Optical (which really only has enough bandwidth for two lossless audio channels, Dolby and DTS are encoding algorithms to compress 6 or 8 separate audio streams/channels into a stereo-sized pipeline). If a signal is encoded, you need a DSP on the
other receiving end of the cable, to make it back into PCM digital audio. Now, I strongly feel that it's worth it for gamers to have a DSP to calculate what a surround setup would sound like once it reaches your two ears, and make headphones recreate that sensation. Check out my Virtual Surround article (2nd Post of this thread) if you don't already know about that.
DAC
Digital to Analogue Converter, turns digital 1's & 0's into the electric pulses that make headphones or speakers work.
All digital systems (CD's, DVD's, games, mp3's, etc) require a DAC before an amp.
Nicer DACs resolve finer details and nuance. It can't bring back data missing from the original file, but accuracy in creating the analogue sine waves at this point is crucial. Going from a cheap DAC (like one built into a laptop, desktop motherboard, smartphone, or game controller) to a nice ($$$) stand-alone DAC can increase the perception of details distinct from each other (we call this separation), depth of soundstage, less bloom or metallic harshness in bass and treble.
Feed it a good sound file, and a good DAC can amaze you by revealing more insight to songs you might've been listening to all your life. You don't need to buy a million dollar statement product by Light Harmonic to get this kind of experience, but I say there are garbage DACs that fatigue and bore the listener, then a bunch of DACs between $60 and $150 that are largely similar and side grades from each other, some mid-fi DACS about $250 and up to get a noticeable upgrade, and there are people that will spend $1k plus on a DAC because many feel that a DAC upgrade provides the second biggest benefit after all your gear is at least mid-fi.
Amp
Amplifier, drives analogue pulses to the appropriate strength and gain (volume) for headphones and speakers, also allows adjustment of volume.
An amplifier comes after the DAC in an audio system, right before the headphone. Sometimes you'll have a unit that is both a DAC and a pre-amp, where you are intended to connect a "power" amp after that (double amping isn't bad so long as you don't have a low-quality component dragging down the whole audio chain).
Nicer ones aren't primarily about "louder," they are for better control to present tones more accurately and provide a solid feeling to bass (and bass extension to really really low notes) and treble, lowering distortion across the whole music spectrum.
Best place to ask about "which amp" would be in the support & review threads about the headphone you have/want.
What is it (definition)?
What stage of audio reproduction is it used?
What effect would an upgrade to this component have?
At what point is something not worth listening to and at what point have you reached diminishing returns?
Closing opinions.
Cables?
What is it (definition)?
What stage of audio reproduction is it used?
What effect would an upgrade to this component have?
At what point is something not worth listening to and at what point have you reached diminishing returns?
Closing opinions.
Cables?
Order of importance
Stereophile musing on how to "design" a music system:
http://www.stereophile.com/asweseeit/system_building_rules151and_how_to_break_them/index.html
