What did the error say?
It might be an issue with your sound card. Go to the the "Output" section under preferences (right next to DSP manager). You can try between WASAPI (push) or (event). It just has to do with how it communicates with your sound card. I believe event has issues with older hardware but worth a try. Also, you can set the output data format to 16 bit first to see if the error goes away (this is on the "Output" page as well). If that doesn't work, well idk, but it will work with the E07K cause that is what I use.
What type of headphones are you using? The E07K puts out a decent amount of power compared to onboard audio and you should be able to definitely tell a difference. Probably not night and day but you will get higher volumes with less distortion for sure. Later down the road if you want to add to your setup there is the E09K (a desktop amp). It has a dock for the E07K to charge and act as the DAC while it acts as the amp. It puts out more power, but you may not need it depending on your headphones, but hobbies always need more things (I have one).
Since you haven't used any other device besides your comp audio, when I say more "power" that does not exactly mean just it gets louder. Even at mid volumes you will get cleaner more powerful bass, more clarity in the mid range, and smoother highs. But all depends on your headphones of course. It might be hard to tell at first with the E07K, but if you have easy to drive headphones you won't be maxing the volume level. Let me know how you like it, and feel free to ask questions, I was in your spot not too long ago.