Why don't higher end amplifiers come with a separate power chassis?

Xs300 past labs Mono blocks for a pair are $85,000.

I think they're 300 W per mono.   Doesn't seem like much power.

really nice car or a pair of mono blocks, or better still, both.

It seems 80% (totally anecdotal number) of the challenges around sound quality comes from the power supply of any complement. Very often the difference between different models from a manufacturer, at different price points, involve extremely complex work on the power supplies.
 

I was wondering if lithium battery distribution is less noisy or if changing to a solid state battery has the potential for less noise. 

@larry5729 "Why do amplifiers come with such cheap power cords.  The power cords they come with might cost $5."

Because the manufacturers know power cords make no difference to sound quality.  They surely have tested.  They don't need or want to waste money on components that cannot improve their product.  They package a good quality regular power cord usually of heavy gauge.  That is all that is required.

Those who wish to spend good $$$$ for no good reason may purchase after-market power cords at whatever price level makes them feel happy.

@larry5729 

Or, to put it another way.  Who knows more about power cords - major amp manufacturers who have been successfully in the market for decades, famous names, that employ dozens of qualified and imaginative engineers, or guys that post here in AG?

@clearthinker

Yawn, and by the way: what‘s this got to do with the topic of this thread? At least get into the relationship between power cable and umbilical, if you must.