Hi Xistented,
To try and answer your question, the Fubar II for example is a USB Dac. So what this means is, you can take your digital music from your laptop/PC/Mac, etc and output it directly to your home stereo system. The one mentioned by Gmood1 is a great DAC.
I actually do own a
Fubar III so I can comment a little bit on that. This Fubar III is also a USB Dac but in addition it has a headphone amplifier built in. So not only can it output to a stereo/home entertainment center it can also output to a headphone. I preferred to spend the extra bit of money to get the Fubar III due to this because I absolutely love the headphone amp. I hear my music like I never did before.
To give you an example, I'm a big Radiohead fan. I was listening to my headsets last night with my Fubar III and I heard "voices" coming up in my music. I happened to be on ESPN at the time so I went to the page and tried to find what clip was playing. I couldn't find anything so I paused my music and the voices stopped. The funny part is it was actually voices within the song that I just NEVER have heard before, even though I've heard "Paranoid Android" a million times. True story... ;) Honestly I can hear every piano key, every drum beat, etc. The amplifier is nothing short of amazing.
IMO, the added money is worth it... but I would highly recommend the firestone audio line. Great products and very affordable.
Hope that helps!
P.S I bought from MA (miniature audio) as well... they have a great return policy so if you aren't happy I'm sure its no problem to ship it back. Personally I've never had to do that because I enjoy my product very much but that may help ease the burden. Best of luck in whatever you decide!