Specifications VS Sound Quality


Surely, I am normally aware of some specs like power output, THD and, maybe some other basics.
But by knowing specs of a component do you really have an understanding of what a piece sounds like?
Maybe that is an obvious no. Not being particularly technically oriented, I want to hear it.
mglik
mapman:

"The main value  of specifications to someone who knows how to interpret them properly  is objectively deciding which components to try ie which components are likely to work best in a specific system with others"

The above makes sense to me but this next part of your post I find confusing:

"Otherwise deciding what to buy is a total gamble with nothing concrete to validate buying decisions other than hearsay or pure guessing"

Seems to me that listening is very "concrete". And it's not unusual for reviewers to state that a component sounds really good even though it does not measure ideally in some regard. 

What is it I'm not understanding about your post?  





@stuartk You can of course listen to hear other places before buying and you should listen to as much as you can both live and otherwise to train your ears. Listening is always the best evidence. But it’s the system making the music and in that room not any single part alone. You can hear what each piece is capable of but that does not tell you what things will sound like at home in your room. So either replicate the system exactly and hope it works as well at home or understand what makes each piece work and work well together including in the room you heard. That’s where specs help to achieve your goals faster and more cost effectively. Only then can you can possibly compare apples and apples correctly when making buying decisions.  
mapman:

Sorry-- I naively assumed no-one would buy gear they couldn't try out first in their room, either borrowed or bought with a return policy! ! !  

Limiting my choices to only those brands I can demo at home (and return if need be) does cut down on my options but I haven't found that a barrier to assembling a system I very much enjoy. 

Thanks for your very patient response. 
Sure well you still have to decide what to try so same  story of course.  Specs help. 
I use many reviews to analyse for some older design that help way more than specs if someone cannot listen to the gear before buying...

I dont regret any of my choices....

"Real"  specs are useful to create standards not so much  for picking  the gear we will love....