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Sound cards are devices used for audio input and output with computers. They essentially consist of a DAC (Digital to Analog Converter), amp and optionally a preamp. They may be either internal or external.
Most modern motherboards have an integrated sound card from a manufacturer like Realtek, VIA or C-Media. They use 3.5mm analog jacks for stereo and 5.1/7.1 surround sound output, line in and microphone input. Higher end motherboards often include dedicated shielding for the audio signals, extra optical outputs and sometimes even headphone amps. Integrated audio usually works fine with the operating system drivers. However, manufacturers provide their own drivers for novelty features like equalizers, channel balance and preset modes.
PCI/E Expansion Card
Add in internal PCI/E sound cards are available from companies like Creative, Asus and TurtleBeach. They often use more expensive components and better shielding than a motherboard's integrated audio. They may also provide additional interfaces and connectors for MIDI, mixers and other audio equipment.
PCI/E sound cards previously targeted the gaming market with extra features like hardware accelerated audio via DirectSound3D, EAX and OpenAL. They claimed to provide better 3D positional audio, thus giving players an advantage in FPS and similar audio critical games. However, offloading audio processing is now considered unnecessary because of the dramatic increase in CPU speed over the years. Furthermore, Windows XP was the last Windows version to include support for hardware accelerated audio through DirectSound. Technologies like Creative ALchemy work around this by intercepting calls to DirectSound3D and translating them into OpenAL calls. The extra 3D effects can also be processed entirely on the CPU through software.
One downside to expansion cards is bad driver support from manufacturers. Manufacturers often release buggy drivers and fail to provide updates for new operating system versions after a few years. PCI/E sound cards are shunned by the audiophile community because they draw "dirty" power from the computer power supply. They are also subjected to a great deal of interference inside the case from fans and other electrical signals on the motherboard. The advantages they provide for gaming are also frequently called in to question. Most game engines now include processing for 3D positional audio and extra effects, so any extra processing done by sound card drivers is usually gimmicky or unnecessary.
External sound cards are devices that may be combination units like home theater receivers or separate DACs, amps, preamps, MIDI and various other audio devices. They usually connect via USB, HDMI, S/PDIF or coaxial optical. Audiophiles may spend anywhere from hundreds to thousands of dollars on this type of equipment. These units often use the most expensive components available along with their own dedicated power supplies. A dedicated DAC paired with a headphone amp is a common recommendation for users of high end headphones with higher power requirements. Headphone amps provide low output impedance resulting in better frequency response and an improvement in THD (Total Harmonic Distortion).
Gaming headsets with their own external sound cards included have become common. Companies like Astro, Plantronics, Razer and Logitech offer USB powered headsets which have an external dongle that performs the functions of a DAC, amp and volume control. They may also provide simulated 5.1/7.1 surround sound via software. These types of headsets are hated on /g/. Surround sound software processing is usually already provided in game engines and designed to work via stereo or hardware 5.1/7.1. Technologies like Dolby Headphone can provide the same simulated surround sound functionality over stereo headphones in cases where it is not available in the game. These units are also usually built using lower cost components to keep the overall price reasonable. Buying a high end pair of headphones, mic, DAC and amp separately is many times more expensive.
Choosing a Sound Card
There are a few main points to consider when choosing a sound card:
- Form factor
- Required features and functionality
- Available connectors
- Options for upgrade and expansion
- Noticeable improvement in sound quality
The point of diminishing returns is where subsequent increases in cost do not result in noticeable improvements in sound quality. Eventually the improvement is so small that it is not worth the substantial cost increase. This point will vary widely for different types of audio equipment. A high end PCI/E sound card typically costs $100-$150. Anything above that may just provide features for musicians or audio professionals that regular computer users don't need.
Home theater receivers and amps can range in price from a few hundred to a few thousand dollars. It is important to decide whether you need amplified speaker outputs. Passive speakers require a separate amp while active speakers have their own amps built in. When using active speakers you will want to make sure your equipment has line level output, so the signal is not amplified twice. Optical is a great choice to pass audio from a computer source to a DAC or receiver. Optical cables are not susceptible to electrical interference because they use light to send the audio signals.
Combination headphone amps and DAC units offer some of the most noticeable improvements in sound quality for their cost. Comparing a $50-$100 headphone amp and DAC to most integrated motherboard headphone outputs will be night and day. $200-$500+ units offer increasingly lower impedance, better THD and higher quality components. Whether these improvements are worth the cost is up to your ears to decide.