OK peeps, now I've done a load of research lately on headphones and DACs and here is my conclusions versus my own motherboard audio.
My motherboard is a MSI B350 Gaming Pro Carbon, it has a decent audio chip of an ALC 1220 and an internal headphone amplifier which says it can power up to 600 ohm headphones. I was debating on whether to even get a separate DAC or just stick with what i thought was a decent on board audio solution. I'm currently using the audio with a pair of Logitech Z623 speakers 2.1 with sub woofer, not the best but a reasonable quality of speaker for my pc audio needs, in addition I've bought a pair of AKG 702 (250 ohm)headphones for my gaming purposes, and replaced these with some DT 770 Pros, more on this later), both of these headphones were around 100.00.
The DAC i actually stumped up for is the SMSL SD793-II PCM1793 DIR9001 DAC Digital Audio Decoder amplifier (56.00 on amazon uk), it's a powered DAC that also uses my on-board audio digital optical out that connects to the DAC port. If your motherboard doesn't have an digital optical out then maybe the fiilo E10k would be a better choice as that is a USB powered DAC and wouldn't require the optical connection although might not quite have the same power as the SMSL although from reading they do seems similar.
Conclusions:
Was the DAC worth buying in addition to the on-board audio solution?
Yes, 100%, if you are going to run a decent set of high ohm headphones then the internal headphone amplifier is not enough to power a set of 250 ohm headphones, the sound is way too low in volume and you will not be getting the full extent of the audio sound from the headphones. I swapped my AKG702s open back headphone (which were damn good) to a pair of DT 770 Pro closed-back (250 ohms). the SMSL DAC powers these well with the volume level turned up to 1pm which gives great sound and volume levels, the 4 on-board amplifier was too quiet to power these headphones. You would be able to power 80 ohm headphones with the on-board audio amplifier easily enough, the MSI B350 with ALC 1220 is NOT capable of powering high ohm headphones from my experience, yes they will work but the volume is not high enough to get what you need from a decent set of quality high ohm headphones.
Was the quality from the DAC better than the on-board audio solution?
Yes, but again it's a little subjective but when swapping my speakers from the on-board to the DAC, there was massive jump in volume levels again but i do feel the detail of some of the sounds definitely seem cleaner and better from the external DAC with the volume increase. For the 50 quid i paid for the DAC i feel happy that i made a very good choice and it wasn't wasted money. The DAC can be used for multiple devices like a PS4 etc thus it can be multi purpose. As an example of volume differences, with the DAC the speakers were at 9.00 o clock and loud, when swapping to the on-board audio I had to turn it the volume knob up to 1.00 o clock to get anywhere near the volume of the DAC.
Any other reasons to by a separate DAC?
I find using the headphone socket on the DAC easier, saves me pulling out the line out from my motherboard to swap between speakers and headphones, yes your case might have a front audio connector but it's likely not as good and then you can end up with possible interference from the other computer components.
Why did i swap the AKG 702s?
These open back headphone were amazing for sound quality but being open back they leaked a lot of sound and my microphone which was a Blue Snowball picked up the leaked sounds which was annoying thus the reason for changing over to the more closed back headphones of the DT 770 Pros. I must admit the DT 770's still do leak sound somewhat for a closed back headphone design but still a lot less than the open back AKG's, also the AKG's seemed a little easier to power than the DT 770s.
Hope this review helps, feel free to ask questions and i'll answer as best i can.
DRITTZ