IIRC the head unit is pre-out only so you would need external amps of some sort (not necessarily Mac ones). The other unit is just volt meters I think (?) so doesn't 'do' anything. The range is limited.
EDIT: - found them! http://www.mcintoshlabs.com/mcprod/shop ... ter+Module
Ah i see, looks cool anyway. When i come to do my next one, i may ask your help with some things such as fitting etc as i dont have a clue about audio equipment, i just know what sounds good,
No problems Louis, give me a shout. I love all things audio!