When you mention the wall outlet, are you talking about the PSC's and not the 2.5 external HDD's (which shouldn't even have one), right? Also, this adapter's USB-A port is white so how can it be USB 2.0 and not USB 1.0? I thought white USB-A ports were 1.0.
You connect the otg cable to the power port of the ps classic so you connect the power adapter of the classic to the otg cable, the power go through the otg adapter. That how the adapter work, supply 5v/1A and give the classic addition usb port to allows like Bluetooth dongle/wifi dongle/usb hdd to work.