Yet another Mac music Question


I have an imac >transparent USB>PS audio digital link III (Cullen mods)>pre-amp. Its sounds good, not great. Here are my questions. Note, I will be purchasing amarra in the next week or so (if that needs mentioning)

I went to the audio midi set up and under the USB out it will not offer a 24bit option. it offers 48K and 16bit as the highest option. Itunes will not read a 24bit flac file even with Fluke. What am I doing wrong?

I would like to set up an external HD to store my itunes library (via firewire). I need to transfer the files that are now on various other external drives in flac format. I need to convert to AAIF and store in the new main library drive. What is the most efficient way to convert the files and link with itunes?
jordanmj
Here's another vote for Amarra. I tried both the Pure Music and Amarra demos and Amarra sounds significantly better with my rig.

PS Audio Power Plant Premier > Mac Mini 2.53GHz/4GB > Amarra Mini 2.0 > Halide Bridge> Cambridge Audio 840C > Acoustic Zen Silver Reference II > Arcam AVR350 > Acoustic Zen Shotgun Double Barrel > Vandersteen 2Ce speakers (combination of LessLoss and VH Audio power cables w/dedicated circuits)
Two more player to try. Mac Only

PLAY. smooth.org/play

Audirvana. audirvana.googlecode.com. (sounds great)
System Preferances ,Sound has to be set to Digital Out , you also need a special optical cable sold in the apple store. To conect to your Dac . This will out the resolution you are looking for.
another option is to get a newer dac with 24/192 asynchronous usb connection. i use a wyred 4 sound dac2 with their device driver to support. you can also use the toslink from the mac but you are limited to 24/96 using this connection. (maybe the new macs can support 24/192 toslink, not sure, but all of my macs don't).