I found the easy way to volume control of Tuneblade using Virtual Device Loopback capture with Virtual Audio Device (VAC).
Here are some screen shorts.
One is Virtual Device Capture.
Line-in Device : Mic 1 (Virtual Audio Cable)
Output Device : Line 1 (Virtual Audio Cable)
And the other is Virtual Audio Device control panel.
Virtual Audio Device (VAC) is paid software, $25. It has the option to enable volume control. Go to control panel and check Mic, Line, volume control.
Then you can control Windows system volume of Tuneblade just like Windows system audio.