One of the great myths about digital recording, and one that I fell for myself, is that you always want to record at the highest sampling rate, and the highest bit depth. This attitude is a bit of a carry over from the days of analog recording, where the master recordings were always of considerably higher quality that the end result. This was done because every step of the entire analog recording, mastering, mixing, and copying process, degraded the sound quality. This is, if you recall, not true of digital recordings, where the numerical values of the digital sound stream are always rendered precisely. While it is probably a good idea to record at the highest bit depth, there may be some problems if you use sampling rates higher than those of your finished product, which will probably be a CD.
    The problem here, is that if you need to change sampling rates, some data will be thrown away, which will create distortion. Thus if you change sampling rates you put yourself in the same boat with the analog recordist, and must deal with distortion and degradation of sound quality at every conversion. Indeed, in the case of the digital recordist, the problem may be even worse. Analog distortion is introduced by the imperfections of the equipment which introduces imperfections in copies of audio wave forms. In the case of digital sampling rate changes, information is intentionally discarded, and the quality of the gear used has little bearing in the results achieved. With analog recording gear, it is possible in theory to have a perfect recording, if the gear is perfect. With digital sampling rate changes, this is not even a possibility, since the change of sampling rate, by design, throws away information. The properties of digital recordings are discussed in more detail in the next section.
    For the home digital recordist, there will generally be three uses to which the computer will be put:

Prerecorded sources
    This will probably be the most common, and can range from the transfer of old cassette, and vinyl albums to digital, to creating a compilation from a CD collection, or converting MP3 recordings and burning them on to a CD. For recordings which are already in some sort of digital format, there is no real need for any special hardware. Even in the case of converting vinyl or cassette to digital, this system is probably a bit of overkill.
    The photo to the right shows my rinky dink little set up for converting vinyl albums, or casettes, into digital. For other sources, such as (cringe) 8-track, I would do something similar. My turntable is at the top of the photo, next to an external 120gb drive. The turntable is connected through the front panel jacks, while the casette deck below is connected via a rear panel jack. My Sun SPARC machine (Unix) shares a shelf with Mogul. Actually, there is an even more rinky dink way of doing this which involves a splitter/converter for the use of standard RCA jacks in a 1/8" input in the back of a sound card.
    For those using a turntable, you may wish to be aware of the signal levels on most turntables, and input lines. For this to make any sense, to anyone younger than about forty or so, a little history is in order. Once upon a time, there were two types of phonograph cartridges in widespread use, the ceramic, and the magnetic. The ceramic cartridge was the original high fidelity type, invented in the thirties by RCA, and the forties by Columbia. These initially used crystals, but soon utilized a piezo system which gave a longer playing time, and tracked at 6 grams, as opposed to the 10 grams of the crystal versions. These cartridges were introduced along with a new style of record, made from vinyl, instead of the old shellac discs. The old shellac discs, used since the turn of the century, broke easily, had a very poor signal to noise ration, with lots of hiss, and had a frequency range of 50 to 8khz (some of the very earliest, before the advent of electronic recording methods in the mid 1920's, had a range of 50 to 4khz). The new vinyl records did not have the hiss, and could reproduce sounds up to 12khz. They also offered, at 45 or 33.3 rpm, longer playing time than the old 78 rpm shellac records.
    The new vinyl albums were great, but by the sixties, electronic recording gear had improved to the extent, that it was possible to extend the range of recorded material. This in turn made greater demands upon the cartridges, and the records. In answer to this, the new magnetic cartridge was developed. This cartridge was capable of lighter tracking, generally two to four grams, and faster response than the old ceramic styles.
    There were two issues with the new cartridges, however. The first was that they had a considerably lower output than the old ceramic types. Outputs varied somewhat from cartridge to cartridge, but the typical ceramic cartridge produced 0.5 to 0.7 volts, though some of the earlier versions made as much as 3 volts. A typical magnetic cartridge would put out 5mv (0.05v), though some could produce as much as 50mv. The Magnetic cartridge also required around 50k ohms impedance, as compared to the 1m to 2m required by the ceramic cartridge. The second problem with the magnetic cartridge was that they did not play flat. They required special equalization in order to faithfully reproduce the recording. Both of these issues were dealt with by the use of a phono preamp, or by a special phono connection on the amplifier.
    Original line inputs were developed for the voltage produced by the ceramic cartridge. When home tape recording and audio gear began to appear, it was designed to operate at this same level, in order to conform to existing equipment. Where a tape source can be connected directly to the line in on your sound card, the phonograph will have to be connected through a preamp, or through a system amplifier. There are some exceptions however. The Sony turntable which I use, has a switch for use with a standard line in. This activates a built in preamp/equalizer within the turntable itself. This is a nice touch, and something that would have been very welcome back in the sixties and seventies when the turntable reached it's peak of popularity. The other exception would be if you could find an old style turntable with a ceramic cartridge, though I strongly recommend against this approach. The old ceramic cartridges were heavy, wore out records, and did not sound as good as the magnetic cartridges.
    CD is a little different. Audio CD can be recorded pretty easily, through my computers built in CD drive. Unlike most computers, this one has the CD connected to the sound card via digital cable, rather than the standard audio cable. What this means is that I can do direct digital to digital dubs and copies. In most computers, CD audio is sent down the cable in analog form, and is converted back into digital when it is dubbed.

Live performances
This can be a real challenge. It is one of the few instances where the break out box, and other features of this card are really needed. There are essentially two types of recordings that this set up will permit. The first is if the wave form, which essentially turns the computer into a digital tape recorder, and the second is through Midi.
    Midi is more like a control system than a music recorder. It does not record waveforms or sound at all. Instead, it records commands. Music is not really played in Midi; it is constructed. This offers some real advantages to the composer, or to the electronic music buff. Midi can score music played into a computer, it can also modify and change the sound, or apply other sounds, including those stored in a sound font.
    A sound font is a collection of sound either recorded, or created by the user. This is similar to the use of a wave table, for playing back Midi over the web. A wave table works by using a collection of stored waveforms, one for each instrument. As an example, the sound card may have a waveform stored for a piano. The midi file will have instructions saying retrieve the piano waveform, and to play certain notes at certain intervals using this waveform. This permits Midi files to be very small, compared to recorded music files, since the Midi file is little more than a glorified text file.
    Sound font sounds can be created by the user, either by recording sounds and saving them off as sound fonts, or by editing sounds in a wave editor, or modifying and processing sounds to change them. Thus you can record a glass breaking,  make it a sound font file, and then use it as an instrument to play back Midi files. You can also use the sound font files as a wave table for live performances.
    Interestingly, you do not even need to use or be able to play an instrument to make music in Midi. You can select a sound or an instrument, designate which notes are to be played, and the measure of the notes, and the music will be played by the computer. Midi is a great tool for setting up background music to set against a solo, or for hearing compositions.
    Recording live performances as waveforms, and then converting them into MP3 files, or some other type of audio file, is made much easier through use of the break out box. The front mounted break out box of the Audigy allows me to set input and mike levels, and to connect through a variety of sources.
    One of the shortcomings of this card is that it really only has one mike line. This means that I can plug a mike or instrument into the mike line, another instrument into the Midi input, and perhaps another into the firewire or direct digital input. This makes doing real studio type recording session rather difficult, unless I decide to go with a simple stereo pair of microphones. Still, a considerable amount of really good work has been done with a simple stereo pair, and this is more than good enough for someone at my skill and involvement level. For those with the knowledge (and the money) to make use of them, more elaborate break out boxes can be added through the front mounted firewire, optical, or digital inputs.
Dubbing and mixing
    Strictly speaking, you probably don't need a really special card to do dubbing and mixing, once the audio stream has been captured; but the better your card, the easier the time you will have, and the more likely it will be that you will be able to find a good software package that will be compatible with your hardware. A good card will also save you some time and effort. Though the computer's CPU will do the actual signal processing, it will be the sound card which converts the signal for playback. Without a good sound card, real time playback is nearly impossible.
    You don't really even need a special sound card to capture the origonal audio either, though a better card will give you a much better sounding stream. Any sound card can be used for doing digital sampling, with the proper cabling. The standard sound card or on board audio in your computer right now can be connected to a cassette, or with a proper preamp, to a turntable. You can also connect from the liine out on your amplifier, reciever, or av center, to the line in on the sound card. This can all be done through the use of a mini plug to RCA jack converter, which is shown in the photo to the right.
    These converters are available at most electronics stores, computer places, or stereo shops, as well as some discount stores. They range in price from about ten dollars, to nearly forty dollors, depending upon the length, the make, and the quallity of the wire. I picked up several sets for about ten dollars each. Some after market sound cards will include a set for free.
    These cables are not limted to be used for connection to standard audio cards. Though the front panel jacks, and breakout boxes are convenient, many high end cards are also connected through the use of adapter cables. I use this type of cable to connect to my casette deck, and to play my computer through my stereo.

    Though there are hundreds, or perhaps thousands, of audio file formats, there are only a few dozen which are well known, and only a few of these are in common use. I do not include streaming file types here, because they can not ordinarily be saved or worked with (though there are ways). DRM stands for Digital Rights Management, and refers to an encryption method used to prevent dubbing or free distribution of files. DRM capable audio file types can be set up to be uncopyable except by an original owner, or by a person possessing an encryption key or password.