The Grado RS1 and the Alessandro MS-Pro share so much similarities in outward appearance, and upon brief listening sessions, many people can’t distinguish the difference in their sound.
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.