That can be a hard question to answer. The Grado lineup contains several models, and there are differences between them. But, to answer your question generically because I've owned the Magnum v.4 drivers in the past in wooden cups -- The Magnum would fall somewhere between the SR-325i and the RS1i. The sound would be better than the 325i, but quite possibly not quite as refined as the RS1i. When I had mine, I also had the Grado HF-2. I thought the Magnum v.4 edged it out by a slight margin, so I ended up selling my HF-2 at the time.
would you say the magnums or the grados are more engaging? which one is more forward