The Audio CD standard was designed from the beginning for sequential access (audio streaming) only. The digital audio was intended to be read in real time, converted to an analog signal and sent immediately to a stereo amplifier.

Reading audio with random access and moving digital data over the data bus without converting it to an analog signal is a feature sometimes not available in older reading drives.

The main problem with reading digital audio data over the data bus is the low degree of seek accuracy provided by reading drives when accessing CD-DA blocks. This is caused by the fact that digital audio data is stored in a different format that CD computer data.

In a computer data block there are 2,048 bytes of user data plus header and error correction information. The header information in a computer data block contains the precise address of the block allowing the drive to precisely seek the correct block before reading.

In an audio data block the 2,352 bytes of the physical block are entirely used for digital audio data. There is no header containing the block address, no synchronization codes, and no error correction. This requires the drive to use the Q sub-code information to find an individual block. Unfortunately, the Q sub-code information was only designed to allow consumer audio CD players to provide audio positioning and position display within an accuracy of ±1 second. As a result, Q sub-code addressing is only approximate.

When searching for a specific digital audio data block, a reading drive moves the laser assembly to a position near where the block should be located, starts reading, and compares the Q sub-code information to the desired block address. When a Q sub-code address near the desired block address is located, the drive begins transferring data (or playing). Most reading drive specifications state that "the actual starting audio address will be within ±4 Q sub-code addresses of the requested starting audio address". In other words, the actual starting audio will be ±4 audio blocks or ±4/75th of a second. As a result a read request using an address of a single block might return any one of 9 blocks (according to drive manufacturer specifications). Some drives may be even less accurate than ±4 Q sub-code addresses.

A second problem with digital audio data capture occurs when the computer cannot accept audio data from the drive fast enough. This is referred as a "buffer overflow", because the reading drive write data into its internal buffer faster than the computer can read data from that buffer. During an Audio CD duplication process, a buffer overflow condition is usually a direct result of the reading drive reading faster than the writing drive writes. It is common to see reading drives capable of reading 4 or 5 times greater than older writing drives can write.

When a buffer overflow occurs, the read operation must be restarted. The next read may not begin transferring data at exactly the same sample (a side effect of the ±4 audio blocks accuracy problem), which can result in a few lost or repeated samples. This lost or extra data can create audible artifacts in the resulting audio disc or file.