Can I connect the SUB to my WiFi network without an ethernet cable and/or the kien app?

Yes, you can.

However, if your network consists of a router and WiFi repeaters/boosters please have a look at this article first.

When you are not able to access (the LAN ports on) your router or when the kien app shows an error message while trying to connect the SUB to your router over WiFi, there is an alternative way to connect the SUB to your WiFi network. This requires the use of the SUB's 'ad hoc' network JB-DIRECT. Here's what to do:

1. Unplug the ethernet cable from the SUB (if it was plugged in the first place) and reboot the SUB by unplugging and plugging the power cable.
2. Wait for the SUB's status light to pulse yellow. 
3. Open the WiFi list on your device (phone, tablet, laptop, etc.) and search for the connection 'JB-DIRECT'. 
4. Connect with JB-DIRECT by clicking on it.
5. When connected, open a new tab in this browser, type 192.168.1.1 in the url bar and hit enter.
6. A network configuration page should show. Scroll to the field 'Choose Your Wi-Fi network' and ignore all other fields.
7. Click on 'Select Option' and select your WiFi network.
8. Fill in the password. Make sure to write it correctly because unfortunately it cannot be made visible. 
9. Click the 'Save' button. A loading icon will briefly show. Keep an eye on the SUB's status light. When the pulsing yellow has turned into a solid white the connection with your WiFi network was successful. You can close the page and start streaming music to your system.
10. When the status light keeps pulsing yellow the password was most likely incorrect. Please try it again by first refreshing the page.
11. If the network configuration page does not show anymore you are probably not connected to JB-DIRECT anymore, because your device automatically switched to an internet network. Go to your WiFi settings and select JB-DIRECT again. 
12. Refresh the network configuration page again. Once it shows up go back to step 6.

JB-DIRECT is the SUB’s ad hoc network that allows you to connect the SUB to your WiFi network. It is not meant to be used to stream music to the SUB. Connecting to it allows you to access the network settings of your SUB in which you can inform it about your WiFi credentials. As soon as you’ve shared your credentials and saved them, the SUB connects to your home WiFi network and stops broadcasting JB-DIRECT. The status light will turn solid white as soon as the connection is successfully established.

In case the SUB cannot connect to your WiFi network anymore JB-DIRECT will show up again, allowing you to still communicate to your SUB. The status light will pulse yellow again. This can happen for different reasons such as your router being switched off or a change in your WiFi Password. In this case, the SUB will try to connect to your home network for a minute, blinking white. If after a minute the network is not found, the SUB will start broadcasting JB-DIRECT (pulsing yellow) so you can set up your SUB again as described above.