There is roughly zero chance that the EFC 00173 would only turn the HK off. Depending on the receiver model, 00173 will either function as discrete power On, or as power toggle. So I guess that you haven't been successful in assigning EFC 00173.
Let's be sure here: If you have a grey OK/Select button, assign Setup code 0110 to AUX. If the OK/Select button is red, assign 30110 to AUX.
Then test EFC 00173 by:
1) Tap AUX
2) Tap Setup (don't hold it)
3) Enter 00173 while pointing the remote at the receiver. When you press the 5th digit (3), the IR signal will be sent.
This should turn on the receiver if it was off. Once the receiver is on, 00173 may either shut it off, or simply leave it on.