From what I've read, the Liquid Gold is the greatest headphone amp ever; crushing everything that came before it. But the 6k price tag is crazy. So, I'm wondering. Do the components of the Liquid Gold justify the cost of the amp, or is it Cavalli's engineering genius you are paying for?
It's kind of a loaded question, because no commercial amp is ever going to be built to cost of the parts. There's always going to be markup since people have to make a living. Some folks think they've got the value figured out because they compare it to DIY offerings they have or someone they know has built, but viable business can't run that way in most cases. There are also quite a few hidden costs with the LAu such as the incredible chassis work (which you have to see in person to appreciate --- OEM it certainly is not). I suspect you'd end up paying a lot for DIY designs for instance if you invested in such flourishes.
Ignoring speaker amps which can cost substantially more, there are headphone amps that cost just as much (Manley Neo-Classic) and even higher (Apex Pinnacle). Looking at the parts list for the Pinnacle for instance, you're not going to see $10k in parts.
In the end I can say I'm immensely fond of the LAu, but in my experience there is no "one size fits all" greatest headphone amp. For me it's the greatest solid state headphone amp I've heard so far by a large margin based on my personal preferences. But someone else may feel the GS-X or the B22 for instance is close enough or even preferable. Also I would say that if you have very sensitive headphones primarily the LAu may very well not be a good fit for you, as it's an extremely powerful amp that was designed with less efficient loads in mind, and for me in SE mode there was too much hum with them (though others have reported little hum under those circumstances --- so it could be a ground loop thing).
Either way, I would strongly encourage people to go out and hear the LAu for themselves and compare it to other stuff, because ultimately only you can determine if it's worth its price tag for you or not.