Saeyedoc, thanks for your comment; I can certainly imagine that browsing a large collection on a little screen would be a pain.
Two folks mentioned Bryston: I'm sure it's a fantastic player, based on what I've read, but it's a little out of my price range and would require purchase of a DAC, since my Marantz SA8003 doesn't have digital inputs.
I've been researching music servers like the Marantz NA-7004 and the Cambridge Audio Sonata NP30. I don't need internet radio etc., but they would both let me attach a USB drive (formatted in FAT32, I know) and both have iPad apps to control them, which I like. If anybody has experience with these or similar pieces, I would appreciate any comments.