have you ever bought stereo without listening first

Yes I bought a system from soundex
in Pa mid 90s
ibought Aurial 10-T speakers cat signature preamp, markLevenson amp
And 36 cdp,transparent ultra cables and power cords and it sounded fantastic. And got 20% off with no tax .i had to drive over 200 miles to pick it up 
but was well worth the trip 
for around $28k cash. Around 2000 I bought an MBL System 
and Kharma model 1 speakers a superb sounding system .imoved to the UK and had my own Audiostore for 8 years .it has been fun ,now I buy Quality designs and just modify them much bigger bang for $$ spent.for much less.

Yes I have...though I have only purchased items that I could return for a full refund within 7 days.

My experience has been positive and in one case I returned the integrated amp because it didn't provide the appropriate volume - I do listen to music on the louder side.  (And I was a Field Artillery Office like the character Bob from Good Morning Vietnam).

In April, I arranged to have a 7 day test period for a McIntosh C2600 and the improvement in my listening enjoyment - sound quality and functionality - was dramatic so I kept it.

Its your money and your listening experience - take some calculated risks.  Your listening room is the best place to understand if the performance of new kit is worth the investment.

I bought the Quicksilver Headphone amp sight unseen from John at Audio Connection....   one the best purchases ever !!!

I bought every piece of my system without hearing any of it beforehand. Just did research and considered the opinions of my various audio "gurus." I try to get complementary components so that the entire system sounds good. That's the goal, right? The only way to truly hear a component is to listen to it IN YOUR SYSTEM before buying it. That almost never happens, so it's always a crapshoot, but it seems to work out. I've never had anything that sounded bad. Most surprise on the upside. My biggest risk was swapping my McIntosh C2200 preamp and Pass X150.8 power amp for an Esoteric F-05 integrated amp. As expected, there was not a loss in clarity or balance in the sound; just provided the simplicity and smaller footprint I wanted.

I buy site unseen/unheard all the time! How can you not nowadays, as there are so few audio stores left. I still remember the Great "Tech HiFi stores" that I frequented in my youth!  Nowadays, I dont feel like driving 100 miles when I can just place an order online. Plus if i do not like something i can return it if it does not work out. Fortunately, most of the time it does work out after careful research and component matching etc. Generally, I have found reviews of equipment helpful in narrowing down what may work.