Ok, first delete the file
/etc/modprobe.d/alsa-base.conf Raspbian Jessie does not use this config file like Wheezy did.
Now, to set the USB sound card to your default card you will need to edit the file
/usr/share/alsa/alsa.conf with the command
sudo nano /usr/share/alsa/alsa.conf scroll down until you find the lines
and change them to
Explanation: USB sound cards are registered as card 1 on Raspbian Jessie. On Wheezy they would be registered as card -2 by default and editing
/etc/modprobe.d/alsa-base.conf would change that.
I do not know if this next step is necessary but without it my card wouldn't work.
Create and edit the file
~/.asoundrc by using the command
sudo nano~/.asoundrc` and change it so that it only reads this:
Now your default audio out (speakers) and audio in (mic) are your usb device.