Sennheiser’s HD25-1 is perhaps a one of a kind headphone, with no other manufacturer offering anything similar to what the HD25-1 has.
The HF2 has a very smooth and liquid sound. It’s like listening to a smooth vacuum tube amp (although we were using a solid-state Beta22 amplifier). Although the MS-Pro has a smooth sound, the HF2 is even smoother. No other Grado sounds like it; not the HP1000, not the RS1, and definitely not the GS1000.