In fact, you ask others to describe the sound which you never heard, I will say it is very difficult. Usually on the forums,they all have some kinds of listening,and above of that,they exchange the comments.
I know your question,which is : After so many years listen on SS amp only,you want to explore something new,and see if the tube sound is better for you. right?
If that is the case,you gotten go and listening by yourself somehow and go back asking the question. That is the normal procedure,in my opinion.