[cherepashka]

that's it...

 

[daltonlanny]

IMHO, not much.
I actually feel that the 880's bass is more natural, accurate and textured than the 650's.
The 650's have slightly more bass extension and a stronger sounding bass, but the 650's bass range is a tad overemphasized compared to their mids and highs in my opinion.

 

[Patu]

It's clearly weaker. I've always had this feeling that DT880 only has the deepest bass but the midbass is pretty much non-existent.

 

[kaushama]

Pre-2005

T880 has less bass than HD650. But more deeper extension and controlled. It lacks the mid bass hump of HD650, which gives Senn apparent richness in bass. 2006 DT880 corrected this to some extension it seems. It is supposed have tad more bass and more tamed trebles making it more balanced than Pre 2005 version. I think Senn House allowed, HD650 to have a mid bass hump to make it popular amongst average consumers.

 

[Andrew_WOT]

With velour pads they are miles away from HD650 for sure. It is said that leather pads alleviate bass weakness to some degree.

 

[vcoheda]

dt880 either version not even close to hd650