What Format Should I Send My Audio to have Mastered?
There are many professional formats that are widely used and accepted by most mastering engineers. They can work with CD-R, DAT, TAPE, DISK, etc... and depending on how you connect to the World Wide Web (usually high speed is a must) you can send it through an internet connection.
The biggest problem that most professional mastering engineers run into with clients pre-masters, especially the one's that are sent in on CD-R's, is how many CIRC errors are showing up. CIRC deals specifically with the issue of error detection and correction. All CD’s are incorporated with CIRC. CIRC is a powerful error detection code that can detect and completely correct almost all errors on a reasonably good disc.
Most times these problems occur if the audio was burned at a very high speed, or by using cheap media, or even the burner itself could be going bad. What ever you do, don't ever burn it on a lap top computer or use i-Tunes to transfer the music.
In GENERAL terms, the higher the speed you burn at, the more errors you will get. Even the opposite is sometimes true as well. If you burn slower that 4X you create an emulsion of the recording and makes the recording prone to different types of errors.
When ever you are in doubt your best bet is to contact the mastering company directly to answer specific needs or questions.