It's not impossible to believe the Xonar outperforms the Behringers, but I'm not familiar with it. If you want a comparison, you might peruse the amplifier forums here.
The ODAC/O2's designer had good things to say about the Behringer UCA-202 plus a number of other products whose prices are well beyond $150. I have the '222, a '202 with a red case and some free software which didn't interest me in the least. You can find a review of the UCA-202 on his Blog. You'll have to search for it because the Head-Fi rules (and Currawong) were and are explicit: No linking to them.
I'm pleased with the sound from my UCA-222. I don't like the tiny, light case one bit. It's designed for professionals, and I found it too easy to overload the output of the FiiO E5 ($20) when they were connected together. So, I lowered the PC's volume to cure the problem. I got more than my money's worth of DAC, particularly when compared with the random collections of parts and fruity, fanciful claims from some other vendors.
Eventually, I'll replace with with an ODAC (or ODA, if it ever appears) but I'm in no hurry.