You can ask the seller for a picture of the back. So much audio is bought without audition anyway. Alit more blind than seeing pictures. However, if you are buying used, you do have a right to pictures of the back and the bottom to check the condition of the chassis.
Seller Listing Pet Peeve
When I'm viewing for sale ads one of the first things I look for are the connections the particular piece of equipment require or can accommodate.
The latest was a DAC that had many photos of the top, sides, front, even different angles of the same view, but not a single photo of the rear. Yeah, I know I can look it up if I'm that interested but the seller could make that point easy on me.
To me it is critical to understand the options/limitations of a piece of equipment from the very start whether it is an amp, preamp, speakers, DAC, etc.
OK, rant off.