PLEEEZE don't encourage anyone!
Ok.
But I'm only half kidding. Because I do think it
sorta makes sense to listen to music the way you like it to sound. But if you are going to spend good money on equipment that enhances the euphonious qualities of your playback system then it makes little sense to buy this device since there is a wide range of very sophisticated effects devices made for use in music production, recording, and mastering that could allow you to dial in what this thing does and a gazillion different things too, any of which might be more to your taste.
Personally I seek transparency because I listen to a wide range of kinds of music and in different situations, it's the neutral ground on which everything stands a chance of sounding good, and I can't be bothered with adjusting the colorations and distortions of my home stereo for every different recording and listening context. But I can imagine that some people might enjoy tinkering with the sound and I grant that it's a defensible practice, given that aesthetic pleasure is the goal and is personal.
But this fuzzy 0 dB amplifier seems more like a fetish. Somehow vacuum tubes became magical. It's as though it is unquestioned truth, according to some ailien priestly tradition accepted by its community, that tubes and only tubes can deliver the particular non-linearities and colorations that deliver maximum joy.