Which to choose: Schiit Modi Multibit, Arcam irDAC or Theta DS Pro Prime?

As a wrap-up to my previous post on "Best used DAC for $250," I now have to decide which way I want to go, and which DAC sounds the best of these three. To reiterate, I'm using the coax digital-out of  my Sonos Connect to the DAC, then onto my Roksan integrated (Kandy MkIII). 

As of this writing, I am considering the following based on recommendations, reviews and comparisons:

1. Schiit Modi Multibit
2. Arcam irDAC
3. Theta DS Pro Prime

The Schiit Modi Multibit was recommended by several members in my other post. My previous DAC was an original Dacmagic. This DAC reportedly sounds very good for the price of $250 new and supposedly rivals DAC costing a lot more $$$. 

The irDAC (vs. the original rDAC) is specifically made to accept direct connection from idevices, as well as the standard coax, optical and USB connections. From what I have seen on recent ebay sales history, they can be had for around my price range. The irDAC appears to be rated very well in sound quality. Anyone out there own one that can comment?

The Theta DS Pro Prime is my oldie-but-goodie selection based on reviews from owners, as well as what I could find in comparisons to other DACs of the time. My only reference to Theta was of the Miles CD Player, which was one of the best sounding player I ever owned--along with the Naim CD3.5. I understand this DAC is "pre-USB" and therefore I will need to use my Monster Cable 1/4" mini-jack to RCA cables for anything audio related on my iPad; other than the app for my Sonos Connect. 

My question is this: Are any one of these DAC going to sound noticeably better or worse than the others? For those who own (of have owned a Prime or other Theta DAC) how would the sound of the Theta compare to the sound of the irDAC and Modi Multibit? 

As for pricing of these items, all three of these contenders can be had for around $270 shipped (used) except for the Modi, which is brand new.