Seeing how the HD650 was transformed by the Balanced Beta22, just for kicks I plugged the HD25-1 to the Beta22 using the same balanced HD650 cable.
The Sennheiser HD25-1 balanced, on the Beta22, startled me just as the HD650 had. The balanced drive, and the Beta22 had transformed the HD25-1, just like it did to the HD650. Balanced HD650 is still superior, of course, but the HD25-1 is just as a monster as the HD650 is. Mostly imaging has been brought to a whole new level, and from my memory, to the point that it betters an single-ended AKG K701.
Of course the HD25-1 is a portable headphone, and when you’re at home on your desktop set up, the HD650 is much more prefferable. The point that I’m trying to make is that Sennheiser had created such a monster driver in the HD25-1 that seems to scale up as well as the HD650, when driven from a killer amplifier and source.
Although if you listen to rock, a Balanced HD25-1 does rock so much better than a Balanced HD650. It has a killer punchy bass that the HD650 doesn’t, an a Grado-like intimacy and forwardness, and the awesome imaging from the balanced drive. Maybe it feels weird to listen to a small portable headphone at home, from a big amp like a balanced Beta22, but do give it a try. I think it’s a killer set up for rock.