Dear Julie,
First, I wish to offer you my deepest condolences on the passing of your husband and am sorry for your loss.
Secondly, I wanted to mention that I am also local to Philadelphia, located in Wynnewood, and would be happy to assist in any way I can. I’ve been buying and selling used audio gear for over 35 years and used to sell it at retail many years ago.
Recently, I’ve been helping a good friend sell off his high end audio collection as he and his wife are looking to downsize into smaller quarters. I will send you an email to introduce myself and give you my contact information.
As several had suggested, multiple pictures and a list of gear is the place to start and then you can figure out selling options from there. There are several options to sell without fees & I also have a network of local audiophile friends as well that may be able to help in the disposition of these assets.
Again, so sorry for your loss.