When NWavGuy says the Udac measures bad, it's not him being biased. It's an objective approach where it's fair to say that compared to amps that measure well, and as far as measurements go, the Udac fares badly compared to certain other products.
Now the question is whether that means you'll get the change you're looking for with something else. Practically, better measurements equal better performance but there are numerous caveats. I'm not even sure NWavGuy mentioned what he thought about the Udac's sound.
To find out you're going to have to spend money if you have no other options. It's my experience that when you need to spend money to find out something (rather than just buying something because you definitely want it period), it's best to spend as little as possible.
A used O2 combination is a good choice. The fiio e9 measures well as an amp and so does that 30 bucks behringer dac that he mentions in the article. Also the Xonar Essence is a device with pretty good measurements.
Keep in mind though that ultimately, those differences are all rather minor. I never went from one amp to another and noticed a huge improvement in clearity or god forbid soundstage, unless I take my worn out 20 year old entry level mitsubishi integrated with insanely bloated bass and no treble as reference.
For example, my little dot (which was supposedly voiced with certain headphones in mind, which makes alarm bells go off because it smacks of a 'design by ear' approach), of which the measurements are unknown, sounds pretty much similar to my e9 and only a little different than my marantz integrated. And those are varying topologies.