Cary DMS 700 vs Aurender A300

I believe you're referring to the Aurender A200 as it is comparable cost wise to the Cary DMS 700.  I can't speak of the Aurender as I've never heard it, but the Cary DMS 700 is a real sleeper.  I've owned it for over 2 years now and have no regrets or inclination to consider anything else in this price range.  Cary DMS 700 is made in USA and rarely comes up for sale on the used market and  Aurender is made in Korea if that matters.  Be aware that Cary can do Roon, Aurender is not Roon compatible to my knowledge.

My two cents: when I was in the market for a streamer/DAC, I gave the Cary DMS 700 serious consideration. (I even attended AXPONA that year to listen to it in an optimal setting.) One clear feature it had, in my estimation, was its being Roon ready. Ultimately, I decided on the Lumin T2, which has served me well. The Lumin unit has recently been upgraded to a T3, and I recommend you consider it as a possibility for you. While the Cary unit has much to admire, it is quite costly.

In reading the reviews of their products on the Cary website, I found interesting the comment regarding unbalanced vs. balanced outputs. The sense I got is that its noteworth performance is somewhat dependent on using the balanced outputs. Consequently, don't lay out that amount of money unless your preamp has balanced analog inputs.