Innuos Pulse Incoming

Thanks for all responses so far.   Can anyone explain what a S/PDIF is, was told it was digital coax.   I have a Coax cable now that attaches Bluesound to Mac, but it soesnt say anything about S/PDIF in it.  
 

S/PDIF

Overview

S/PDIF, or Sony/Philips Digital Interface, is a standard for transmitting digital audio between devices like TVs, CD players, and amplifiers. It's a uni-directional format that supports compressed surround sound and uncompressed stereo audio. S/PDIF is known for its high fidelity and better sound reproduction because it doesn't add noise to the audio signal. It can carry two channels of uncompressed PCM audio or compressed 5.1/7.1 surround sound like Dolby Digital or DTS. 

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Yes your coax is an S/PDIF along with your optical out. 
my guess is you’re gonna go on a USB cable search but then that’s just my guess enjoy

On the connection questions the best thing if you can is to try each and see which sounds best. On the ethernet question I was astonished at the great sound I got from Bluejeans ethernet cables for all of $17 for 1M.

On my Pulse I find the USB connection to sound the best. It may depend on the cable you use for each connection though. I have a great digital coax cable and tried many USB cables (all under $300). I liked the Analysis Plus Purple Plus the best.

Hi , I have the Pulse Mini with a LPS into a Yiggy with the newest USB card. As said above you will have  to decide which clock to utilize. I went with the USB, but you have the MAC. Maybe check online with the Cable Company as they offer advice and have a library you can rent from. For me I went with a Wire World Starlight Platinum USB. When I want a softer presentation I use a Cardas Clear. Happy Hunting , Mike