Cannot choose monitor to play audio to, always uses HDMI-0

I use a Geforce GTX 1060 with driver 381.09. I have two monitors attached, according to xrandr one is on HDMI-0 and one on DP-0. Both are fully capable of playing sound, and this works on the same machine using Windows 10 dualboot.

aplay -L gives:
[…]
hw:CARD=NVidia,DEV=3
HDA NVidia, HDMI 0
Direct hardware device without any conversions
hw:CARD=NVidia,DEV=7
HDA NVidia, HDMI 1
Direct hardware device without any conversions
hw:CARD=NVidia,DEV=8
HDA NVidia, HDMI 2
Direct hardware device without any conversions
hw:CARD=NVidia,DEV=9
HDA NVidia, HDMI 3
Direct hardware device without any conversions
[…]

But no matter to which device I’m playing, the sound is always sent to the monitor connected to HDMI-0. What would I need to do to be able to play on the other monitor?