I know I am going to generate many an irate response from among the headfi members in saying this, but the stock DT1350 whilst great has that tunnel-like soundstage. I didn't really like that as I have grown accustomed to the T1 and Hd800 at home.
This wood mod eliminated that tunnel-sound. It renders a wider soundstage with greatest improvement in the treble presentation. Highs are very well-extended, full and has that body you typically find in higher-end and more expensive cans. And the bass while lessened in quantity with the opened back, has that natural decay that I love in 1350's bigger cousin, the T1.
All told, the signature deep bass of the 1350 is still there but only lesser in quantity. The highs are given the much needed extension and body sans the closed chamber reverb. Mids remain largely unchanged (at least that's my half-hour listening impression).