Hi all... I intend to use my iMac with an external amplifier fed by the optical output. Two things: Will I need a toslink to optical 3.5mm converter plug for the iMac side? Or does the iMac have a standard toslink connector? Also can the inbuilt speakers be controlled independantly of the optical out? Would it be a case of pressing 'mute' on the keyboard and the iMac continues to output the optical at standard volume (0dB, or line out volume?) to be controlled externally by the amp? Or is there a mixer panel to determin what the software volume relates to? Thanks!