neutral AND funky, energetic, fast, bodied but never agressive nor boring ... I often think to you and your advice when I listen to My sig pro . Many manu thanks!. I 've the "wow' effect each time I put it on my head and switch on my music. I'm using now a Aune T1 ( hybrid tube DAC/amp) with a Russian 6N27P tube to drive my sig pro and In my opinion this little and unexpensive dac/amp works very very well with the sig pro . it brings a touch of warmth and smoothness, an airier and more refined overall sound and soundstage ... I found a near-perfection combo to my ears. I would like to upgrade I really don't know what to upgrade from what I have now.