Going back to your prior post, maybe I should have asked you to clarify what "really crappy stereo" sounds like to you, since it's a subjective topic. For some reason in my mind I thought of phone call hold music, because that's what the headset profile sounds like. A2DP with the default SBC should sound like a 128 kbps MP3, or thereabouts.
As for your setup, Bluetooth settings are very limited when using the default Windows drivers, but there should be checkmarks for the profiles currently in use by a device.
More importantly, while Bluetooth has native Windows support, I don't believe AptX does. I believe you must install CSR's software that came with your Bluetooth adapter to even get AptX working. Installing the software might automatically fix the problem just because AptX will then be automatically enabled (similar to how your Galaxy S3 went straight to AptX).