I have never heard the Esoteric or the Sonica. I do own Oppo 105 and 203, and I’ve been told that the Sonica essentially is a beefed up DAC from the 105. When I ran the 105 into two other DACs, the Mytek Manhatten and the Bryston DAC3, the improvement was huge. The Esoteric cost about seven times the Sonica so I expect that you will hear a major improvement. Whether that will be the best use of the extra dollars is something that I can’t answer having as mentioned never heard the Esoteric, but the Esoteric never seems to be mentioned in Forums for DAC recommendations or DAC streamer combos in that price range.
