When I bought my Freya I just ordered the stock tubes and then went looking for something else that could help improve the sound at a reasonable price. Let's face it you probably don't want to spend more for the tubes than what the preamp cost. You definitely do not want the LISST if you want the sound of tubes. I had already tried the Early Russians in an Atmosphere amp that I have and found them to be a very good bang for the buck tube. Better than the Tungsol which I have also tried. I'm sure the Tungsol tubes Schiit sells are matched and a good value, but IMO they're probably no better than what you can find elsewhere (Upscale Audio for example), and again the Early Russions are much better for only $5 more.
I have no experience with the tube lowrider speaks of but but kinda doubt that's what Schiit is selling.