He wants to
avoid, not force, downsampling. Forcing 44.1k is downsampling relative to 48k.
I don't think you can force the sampling rate to some high value from UAPP itself. All you can do is set it to "Variable" so that it follows the file you're playing and the available rates of the DAC you're using. If you set "Android default" you're still going to get something like 44.1 or 48, because those are the typical Android defaults.
LE:
Oops, you actually can force it to go high: as high as the DAC supports (option "Upsample to highest rate"). Theoretically that may degrade the quality somewhat if the file you're playing has a lower sampling rate than the DAC's maximum, but if you're upsampling from, say, 96k to 192k I wouldn't expect much in the way of audible artifacts.