@macming I did make the switch. I am very happy with the STR preamp! Especially with the PS Audio M700 amps. These are not in my trade/sell rotation. I go through a lot of gear and I don't tell people locally I have these because i dont want to give them up.
That said, I cannot honestly say that I actually HEAR a difference in the pre/dac section. Anthem claims they use much better parts etc and maybe they do, but how audible is that? I wouldn't say "night and day" and you won't hear any difference if you're using a bad source, have a poor room, or speakers that aren't up to par.
So, I THINK I have improvement yes.. Some systems might show it more. But, the integrated amp is stunningly good for an integrated.