I use one with a Garrard 401 in a heavy plinth, and I've switched out the MDF shelf for a heavy maple platform as well. The way I've ensured stability is to attach the Target steel shelf to a hardwood board (secured in all six of the connections), and then I attached the hardwood board across three studs.
I used a red oak solid plank 23" by 12" by 1/2" and was able to span three studs by starting alongside a window molding. It looks great since I stained the hardwood backing a similar color to the maple shelf and the plinth. I may not have done it if I had to make it 34" wide (i.e. the span of 16" studs x 3), but I was lucky to have the window in the right place. A 34" wide board would not have looked nearly as good.
You should be fine as long as you use a good stud finder and hit the center of the studs, and also use wall anchors for the center connections.
I used a red oak solid plank 23" by 12" by 1/2" and was able to span three studs by starting alongside a window molding. It looks great since I stained the hardwood backing a similar color to the maple shelf and the plinth. I may not have done it if I had to make it 34" wide (i.e. the span of 16" studs x 3), but I was lucky to have the window in the right place. A 34" wide board would not have looked nearly as good.
You should be fine as long as you use a good stud finder and hit the center of the studs, and also use wall anchors for the center connections.