As a generality, an external sound card is to be preferred in any case, given the frenetic digital activity going on inside a computer. Digital emissions from the Mac are nominally minimized according to regulations and RF shielding, but it is still a violent environment within, able to play merry Hell with entering analogue signals. Therefore, Griffin iMic, Onkyo, ESI U2x and other cards with USB connection to the Mac are potentially a great advantage in terms of separation from noise pickup. Digitizing with a PCI card, even a superbly competent card such as a MOTU or ESI's Juli@, has one base at least loaded against it because the card is internal. It comes down to how fanatical you are about giving your sound the best possible chance in life.

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