Convert USB to SPDIF

I searched the Forums but didn’t find anything recent on this.  I wish to add a 2010 MacAir running Audirvana Plus to my basement system.  NAS and router are upstairs.  My AVR is anAnthem MX5 channel that doesn’t have a USB input.  What is the best way to convert USB to SPDIF?  I found some cheap converters but would like add something decent...
The Berkeley Alpha USB and Denafrips Gaia converters are both well regarded, but probably overkill for an AVR.
I have a Melodius Audio MX-U8 that replaced my Musical Fidelity V-Link II.
The V-link II is 24/96.
I will sell it if you are interested for $100 usd which includes shipping to the lower 48 . Contact me if you are interested. It is actually very good sounding
yeah, I don't want to spend more on the converter than the price of the AVR.
djones51 suggestion might work, although that is getting towards the price of buying a budget streamer.  I just wanted a quick fix to replace my Node2 in this system which is dead in the water after the last update and since I am not using this MacAir with Audirvana loaded at the moment I thought I might try to repurpose it.  There is a bargain basement convertor out there for about $20 but that can't be much good.  I have a first gen Audioquest Dragonfly that I am not using maybe I can stick an RCA cable (are they called mini cables?) that is single ended on one side and double ended on the other and attach to the analog inputs of the AVR while I try to get the Node fixed
Schiit Eitr. Add an Acoustic Revive REM-8 to clean up the AC noise and the quality is superb
You can get low cost options like a  Behringer UCA222 for part time duty. 
I've got the vlink mentioned above.  How about $50 shipped?
Try reset on the Node.
It worked on mine.

Or just try the $20 one short term.
You're already sacrificing SQ playing a laptop.
The laptop-Dragonfly-mini cable into the analog inputs of the AVR seems to work o.k.  I had bought a mini cable from Best Buy late yesterday but then didn’t have much time for comparative listening.  I don’t use this system for streaming very much, it’s primarily for video and surround sound music.
  Searching through my pile of unused equipment I came across a Musical Fidelity VLink.  I had bought one when it came out because I had a DAC that didn’t play asynchronous USB.  If I remember it worked for a few days then would sputter during replay.  I think it was a demo unit from a dealer who was going out of business so no refund.  Ultimately I bought an Oppo 105 which had asynchronous USB