I've never used foobar for bit-perfect playback, and from what I've seen on the foobar support forums that's not a very common scenario for foobar users either. The reason foobar is so far beyond the competition is because of its simple but highly customizable scripting features - particularly relating to file management and tagging. It's also got a huge list of smaller features that don't come together in any other player / library management software... ReplayGain scanning, applying RG to MP3s without re-encoding (useful for devices that don't support RG tags), a nice way to assemble stats on pretty much any aspect of your library or tracks you select in any combination (sample rate, bit rate, codec, running time, file size...). or to sort by any of those in the playlist view. The converter functionality is great too, you can use any command-line encoder with it. Processing with DSPs during the encoding process... being able to script the file name and folder path during the encoding process. I could probably go on for quite a while.
Other players might have a subset of these features, but they're all missing big chunks of what foobar does, and almost all of them use way more system resources. I checked out the latest version of Amarok recently, and got blasted with a gaudy inefficient UI and the program trying to connect to something over the internet for some reason, without me even having clicked anything yet. There's really nothing to compete with foobar on Linux (or on Windows for that matter). It's in a class of its own and has been since at least 2006 when I started using it. I'm frankly surprised there is no open-source equivalent - all the OSS developers seem to be stuck emulating Winamp or iTunes.