Well, right now I have two CIEMs (JH13; JH16 with the JH3A and two full size headphones (AKG501; HE500) that I use regularly and, basically, the Solo CLAS improves the sound quality significantly for all four (just comparing sound quality with and without the Solo CLAS for all four phones). But then I think most DACs do, regardless. So, it boils down to if you want and can afford some sort of DAC and how that will impact the relative portability of your rig. For sound quality improvement, there is no argument for me.