I am currently using JBL LSR 308 directly plugged in to my pc and I'm trying to further improve the audio quality. I need a balanced audio interface which will output clear audio with minimal interference and use the speakers to there potential. Would a Scarlett solo be a good choice for me considering I am not looking to record audio or is there any other similarly priced alternative interfaces that are better.
You won't really get better sound unless you are getting sound issues now like hiss or popping/crackling. A lot of the sound quality comes from the source you are playing, in fact the better your equipment the worse some things may sound because it will expose the poor recording. I recently got a new set of headphones and there are some things I could not listen to on them because I would hear the background slapping of the bass strings and small extra noise from the recording that my other headphones did not reproduce.
If you have a good soundcard on the motherboard you may want to play around with speaker placement and maybe some room tuning with carpets/wall coverings/sound baffles instead of looking to another sound card.
If you really want to get something then the Scarlett would be find, has the right outputs for your speakers and in theory should be cleaner than the onboard sound card. If you can tell the difference between them is not too likely though but would be up to you and your ears.