It's hard to say what's "missing" without A/B comparisons.
As for the 220SE, I don't even have it at 1/4 on the dial, even on my "loud" listening days. So I don't think lack of output power is an issue. Perhaps if I traded to B&W 802's or such, but that's a different story.
My thought was perhaps it gave it some audio fidelity improvements through the new components (Sabre DAC/ICEpower) that was just released.
So at $3,400, I can get an $850 credit. So I'm paying $2,550 out of pocket for a brand new, 500-watt Integrated Amp with all new components and 3 year warranty.
While I have some experts...I have my Marantz streamer to my amp via Audioquest RCA cables. However, it does have an Optical out...should I be using that?
I see now Amazon has entered the lossless realm today, so that's interesting since I primarily use Tidal.