I've owned all the 1-5 Nait versions, some models more than once (Nait 1 2x, Nait 2 CB 1x, Nait 2 Olive 2x /one with MM, and another with CD, RCA inputs/, Nait 3 2x) before the 5si and must say it was the 3 that impressed me the most. this, perhaps, could partly be attributed to its higher power output than of its predecessors (30W/ch for the 3 vs. 12-15W/ch for the 1 and 2, depending on the source of the info), but IME the 3 was the most versatile of the bunch regarding ease with musical genres and compatibility with speakers. to note, I used the Naits with various Royd, Rega, Heybrook, and Triangle same-era speakers (but no Naim ones - they simply couldn't cut the mustard for me). additonally, I've never heard the R version but some people here in this forum said that it sounds even better than the plain-vanilla 3. hope it helps