I have been using a Chromecast Audio (CCA) as the source for my DarkVoice 336SE for a couple of months now and I'm impressed.
This may hurt my Audiophile cred (not really a problem as I have none), but I find the analog connection of the CCA to be exceptional for my needs. I use Google Play Music for most of my listening but I also use Plex for listening to my FLAC collection.
I have used the CCA optical out via my Aune X1S and Audioengine D1 to the DarkVoice and don't hear any noticeable improvement compared to the CCA directly to the DarkVoice via 3.5mm to RCA cable.
IMO the CCA is a capable source for your amp and an unbeatable bargin at $35.