In the article by John Vanderkooy and Richard Mann, there was an error in the description of the operation of the Focusrite Scarlett 2i2 soundcard. Specifically, the article reported that the Scarlett 2i2 would invert the signal which is not the case. John's correction can be read here. Apologies to Focusrite; as noted in the article, this is a high quality product.
You are encouraged to download and study the full Focusrite comments and corrections.