Why does sound stop and how can I prevent it from stopping?

Question

I have a Focusrite Scarlett 2i2 second generation USB card. The manufacturer doesn't supply a Linux driver. It works well right out of the box with Ubuntu Gnome 17.04, but stops after few minutes of playing sound. The card is ok, works well under Windows.

I checked out this article: Focusrite Scarlett 2i2 Flawlessly Working on Ubuntu with Jack

But I don't hear any difference after using Jack. Sound comes back in two cases, when I reboot the OS or when I unplug and plug the card again. It seems to me like the OS is disabling this device after a while convinced that it's not in use or was unplugged.

It's not power related. USB is still working. I see glowing diode on card's front pannel.

Can anyone help me with this issue?

Edit:

:~$ lspci -nnk | grep -A2 Audio  
00:1b.0 Audio device [0403]: Intel Corporation 5 Series/3400 Series  
 Chipset High Definition Audio [8086:3b56] (rev 06)  
    DeviceName:  Onboard Audio  
    Subsystem: Samsung Electronics Co Ltd R730 Laptop [144d:c06a]
  Kernel driver in use: snd_hda_intel  --  
01:00.1 Audio device [0403]: NVIDIA Corporation GT216 HDMI Audio   Controller [10de:0be2] (rev a1)  
    Subsystem: Samsung Electronics Co Ltd GT216 HDMI Audio Controller [144d:c06a]  
    Kernel driver in use: snd_hda_intel  
    Kernel modules: snd_hda_intel  

$ aplay -l  
**** Lista PLAYBACK urządzeń ****  
karta 0: MID [HDA Intel MID], urządzenie 0: ALC269 Analog [ALC269 Analog]
  Urządzenia podrzędne: 1/1  
  Urządzenie podrzędne #0: subdevice #0  
karta 1: NVidia [HDA NVidia], urządzenie 3: HDMI 0 [HDMI 0]  
  Urządzenia podrzędne: 1/1  
  Urządzenie podrzędne #0: subdevice #0  
karta 1: NVidia [HDA NVidia], urządzenie 7: HDMI 0 [HDMI 0]  
  Urządzenia podrzędne: 1/1  
  Urządzenie podrzędne #0: subdevice #0  
karta 1: NVidia [HDA NVidia], urządzenie 8: HDMI 0 [HDMI 0]  
  Urządzenia podrzędne: 1/1  
  Urządzenie podrzędne #0: subdevice #0  
karta 1: NVidia [HDA NVidia], urządzenie 9: HDMI 0 [HDMI 0]  
  Urządzenia podrzędne: 1/1  
  Urządzenie podrzędne #0: subdevice #0  
karta 2: USB [Scarlett 2i2 USB], urządzenie 0: USB Audio [USB Audio]  
  Urządzenia podrzędne: 1/1  
  Urządzenie podrzędne #0: subdevice #0  

$ pactl list short sinks  
0   alsa_output.pci-0000_00_1b.0.analog-stereo  module-alsa-card.c  s16le 2 k 44100 Hz  SUSPENDED  
1   alsa_output.usb-Focusrite_Scarlett_2i2_USB-00.analog-stereo module-alsa-card.c  s32le 2 k 48000 Hz  SUSPENDED  

And yes, card is selected, is not muted, sound is being produced for a minute or so while playing from youtube or spotify. Then stops.