I've been doing ABX tests using the foobar2000 ABX utility. Taking commercially produced CD's, I upsample them to 192 kHz @ 24 bits. Then I ABX the original 44.1/16 file against the upsampled one. The files are converted using Sound Forge 10's included tool from iZotope, their 64-bit SRC. I've done it with the default settings (filter steepness 32, alias suppression 175) and with the "highest quality" settings on the slider (filter 150, alias 200), with equal success. I've tested against pop music (MEG, album 'Room Girl', tracks 'G Ballad' and 'Groove Tube'), and against classical (Christopher Parkening performing Albeniz with London Symphony), with the same success. Here's the truly weird part: I've been using my Beyerdynamic DT 770 Pro's through Schiit Asgard2 for the most part, but today I replicated my results again using cheapo earphone plugs, from the output jack on a plain-jane PC with no soundcard (just built-in motherboard chips)--same success. The plugs provide decent isolation, but that's about it in terms of quality. One sample result is listed below, I have several others. http://i.imgur.com/UdWshKh.png Does anyone else have a successful ABX result to cite for upsampling? Does anyone have any suggestions for upsampler settings? Filter steeper or gentler? Anti-aliasing? etc Comments, hearing test challenges welcome.