USB connection to Dacmagic?

Hi, I would like to ask question in relation to my audio settings. I normally play music through itunes and sometimes play Flac files through Amarra. I am not really serious listener just enjoy a good quality music.

My current setting at the moment is Imac - USB connection to DacMagic - DacMagic - Aktimate Mini.

I am looking to purchase either Hiface USB or Audio GD Digital Interface from my Imac to DacMagic. My choice is toward purchasing Audio GD Digital Interface B with PSU.

I am a newbie in audio system so I had a few questions:

1. I wonder if my Aktimate Mini is good enough or will it become a bottleneck with Dacmagic and USB Spdif connection?
2. From my understanding Audio GD is only asynchronous USB device, will my Dacmagic is not good enough for Audio GD DIgital Interface? (I read through threads that Dacmagic is kind of entry level Dac)
3. If I end up purchasing Audio GD Digital interface will that kind of replacement for sound card; so in future I don't need to invest in soundcard just use USB-spdif device to connect to my stereo system? What is the difference of using soundcard or not since USB spdif is already good enough?
4. Does the difference quite signiface using USB-spdif device considering my system and my listening usage?

Hope you guys can help me answering newbie question .

Thanks a lot guys, I will give it a shot. I didn't know that Imac headphone out also acts as optical out.

Question with the toslink cable? Should I use glass toslink to achieve 96khz or any good toslink brand should be able to achieve 96khz ?

Got my toslink cable but I wasn't sure what happen when I try to play on higher sampling rate. The music sounds like been fast forward, is that because of the issue on the cable? (kinda like hear alvin and chipmunk voice). Is it maybe because the original source from 44.1khz then I try to upsample it 96khz then sounds like fast forwarded. SUBMIT

Thanks, I just use xld to convert mine. It does convert it without any issue.