I had the same problem and a friend of mine, who owed me a favor, and I scaled up a set of bookcase plans by Norm Abrams from “The New Yankee Workshop”. We made them a lot deeper to accommodate the components but only wide enough to accept 1 component per shelf.We constructed 2 of the altered bookcases and I cut a piece of 3/4” birch plywood to the same depth as the book cases. Mounted between the bookcases cases it supports my turn table and my small record collection. I have a small led tv mounted to the wall along with a sound bar.
The room isn’t very big so that covers one wall completely with the speakers tucked in next to the book cases. Not near as pretty as the BDI furniture, which I was drooling over but functionally it has served me well for about 30 years and counting.