These are literally plug and play type modules.
Unless you get into trying to mod them in some way (I've seen people talk about changing a resistor to effect the gain) or build your own input buffer stage...
That is way outside my paygrade, though.
However, I will say the product being offered by Buckeye really does seem legit if you aren't looking for additional flash. And the differences between Purifi and Hypex are really just academic in that they are both exceding what the human ear can detect in terms of pure performance.