A used Naim UnitiQute appears to meet all your requirements. Other units to consider would be the PS Audio Sprout, and the Sonos Amp. Neither the Sprout or Sonos are "killer" pieces, but both will attach to a Mac. The Naim has much better sound, but will cost about 2 to 3 times more.
Also, count me as a +1 regarding a used Ax-7e. I have one of these and concur with the comments from others. The Ax-7e is a great value, especially if you can find a used one for sale in clean shape. Hope that helps.
Also, count me as a +1 regarding a used Ax-7e. I have one of these and concur with the comments from others. The Ax-7e is a great value, especially if you can find a used one for sale in clean shape. Hope that helps.