What is the most overlooked consideration?

Not to hijack since it was mentioned twice I would pose this to the repliers commenting on the "musicality"of a component..How the H do you judge a components musicality if you are considering it for purchase & don’t yet own it?
ONLY the "usual"audiophile criteria can be used at this point of the process!

This is by no means the primary consideration, but as a retired person on a comfortable but fixed income, one of the things i always consider is whether a component is desirable by others and can I purchase it for a good price. Can it be flipped quickly, without losing money or at a slight profit.

SYSTEM synergy

It may be hard to define in words, but you know when you have it (or lack it.)
A newly selected audio component inserted into your rig can create an audio performance change now ranging from poor/non/optimal to good/ ​​​​​improved.

Think all the daily AGON forum posts asking for new components recommendations.The conflicting responses range widely and all too many simply reflect personal fave bias.

Just because a touted Brand X component seemingly works well in a Respondent system, is no assurance that it will succeed in OP’s system.. “ One size does NOT fit all”…

All the things previously mentioned are considerations, I also need to see quality parts, I also much prefer point to point wiring in pre's, amps, speaker crossovers, power supplies extremely important.

A mis-match of the preamp and the amp that can hinder the overall performance.