Doug,
To connect the Schiit Modi 3+ between your iMac and your system, you should just need to buy the Modi, get a USB cable that connects between your iMac and the Modi and a pair of standard interconnect cables. You should already have the interconnects. You can use the ones from your CD player if you choose.
Regarding the other DACs on the Schiit site, just get the standard Modi 3+. No need to buy the multi-bit option (it's showing out of stock anyway). $99 and you should be good to go.
Good Luck and Best Wishes.
To connect the Schiit Modi 3+ between your iMac and your system, you should just need to buy the Modi, get a USB cable that connects between your iMac and the Modi and a pair of standard interconnect cables. You should already have the interconnects. You can use the ones from your CD player if you choose.
Regarding the other DACs on the Schiit site, just get the standard Modi 3+. No need to buy the multi-bit option (it's showing out of stock anyway). $99 and you should be good to go.
Good Luck and Best Wishes.