Hi,
Im not familiar with the Sparky board but when you like to run the Piano 2.1 in 2.0 Mode you can not select the Piano 2.0, which is a different sound card. When the Piano 2.1 is selected(in the Allo Plugin Tab), you should see some adjustment sliders. One of them is there to switch the Subwoofer mode, as you can see on this screenshot: 