So I just tried mixing prepared Soylent with apple cider in a glass (~1:1) which was OK, but not worth repeating. Also with goat milk (~1:1) and that was pretty nice. I then tried adding more Soylent to the glass and it was still pretty OK. I didn't want to make a whole pitcher, and while flavor dilution is a factor, it gave me enough to go on to try making my next pitcher mixing in goat milk in place of water. I wanted more Calories, and this way I'll get a little more saturated fat, which Soylent is low in. I didn't measure, as I'm still experimenting with the basics, but it can't be worse than plain Soylent.
Edit: I poured water in until it looked about the height I remembered. It was approximately 2 cups of goat milk.
Yesterday I had the worst gas in smell and volume. Goat milk was a bad idea in that regard. The Soylent flavor was milder and had less aftertaste, while being creamier. Unfortunately the aftersmell was abysmal. Today I'm on regular Soylent and things have calmed down immensely.