"Scaling down" for any other reason than desparate need for money, or moving to a smaller space, is rather foolish IMO.
First, if all the person wants is different sound, then just dumping everything and starting over is silly.
This is the "Gee I liked music when i had a simple setup, so I will go back to that" syndrome. (it does not work...))
Thinking this is too much stuff,, then selling it is taking a huge money bath, plus the wasted time. The smaller system will not please anyway, and eventually the owner of the downsized will go right back to what they had before.. After the fixation with whatever made them downsize passes.
Personally I would suggest just 'ignoring' the stuff. Think of it as another pile of junk you own.. so what. Get over the emotional issue making you want to get rid of the source of the irritation, instead of finding the reason for it being irritating.
The most common so called reasons are displeasure at the result: that is you are not happy with the sound, even though you SPENT $$$, so in a pissed off mood you want to sell it all.
Or, You find a new partner, who does not like the stuff.
Other reasons I have seen are going deaf(er) and out of self spite selling everything (this is the cutting off your nose to spite your face method)
Having to move to a (much) smaller space: this is the one valid reason I can see for moving to a smaller setup.
Though really one can have a pair of giant monoblocks and huge speakers in an 11" by 12" space easy..
The only problem with big electronics in a small spavce may be the amperage available may not be adequate.
So you can see, I am not big on tossing years of effort chasing some pie in the sky ideal of a smaller is better...
As i dream of bigger amps and speakers...