@ghdprentice Funny you should suggest that. My big system consists of a CD9, Ref Phono 3, Ref 6SE, and '160S.
It's hard to put a number on it but I really feel the i/50 gets me 80% of the way there or even a little more.
No plans to downsize my system but it's got me thinking about diminishing returns more than ever.
Your point is valid. I know the maggies are a tough load to drive and I haven't heard the .7s with an i/50. I will say that I've got the i/50 in a fairly large room (17x35) hooked up to a pair of Snell k.5 monitors (same 86dB efficiency as the .7s) and it drives them splendidly. I have gotten close to maxing out the volume control on very quiet recordings but haven't found myself wanting for more power.