Here's a detailed explanation and examples about ffsox upsampling capability http://in-ffsox.sourceforge.net/
And here's http://mir.cr/3RX4ASPE my configured xmplay with plugins utilizing that with xmplay's built-in SRC doing the downsampling to 44100Hz, the sampling rate of most of my collections, also with wasapi and asio (I use wasapi). It's portable so you don't need to install anything, just unzip and run xmplay.exe.
I *do* hear the difference but I'm curious to hear what do you guys think.
Lastly, virustotal show some warning to my upload (as it did to numerous other legit program) it seems it's because I use portableapps appcompactor with the ffmpeg dlls to fit it into my tiny ramdrive. You could of course just configure xmplay yourself if you don't believe me, I'm only doing this to spread the technique and hear your opinions.