I know its a cheaper amp but the E11 warms the R-50 up just enough to make them perfect for the way I like to hear them and opens them up just a little as well.. Now I don't know of a better all around amp that will give them some warmth but I'm sure if you research enough you can find one.
I agree with this. The R-50 with the E11 are a perfect match.
My initial impressions of the R-50 vs. EPH-100: R-50 has really amazing texture and detail especially for string/brass instruments. Vocals are airy and warm, ever so slightly forward but not agressively so to shrink the soundstage. The EPH-100 though not quite as detailed, does have a better soundstage and 3D presentation. I will have to have more head time with these before I write a real opinion about them, but so far I am really quite impressed. Originally I was only going to keep the set I like the most, I have a feeling I'm going to end up keeping them both and using them both... my poor wallet.