Less bass than the 400i? I disagree and if anything I would the bass qualtity and quality is better on the 400s. I skipped out on the 400i way back when as I didn't dig the bass much as the original 400.
O.K. Maybe not less bass, but to my ears the 400S definitely had lower resolution bass than the 400i.
To be honest, after the first few minutes I stopped critically listening because the overall SQ just wasn't up to the level I was hoping for.
And then when I listened to the 400i, I had no reason to want to listen to the 400S ever again. It just didn't do anything for me.