There is a reason why the last free soundtrack release was called “Part 1.” Valve was obviously planning more to expand their “Songs to Test by” collection. And now they've officially done it by releasing Part 2 of the compilation for free, which brings with it another 18 tracks. The soundtrack can be downloaded at Valve’s official website.
In addition to the 18 songs included in volume 2, Valve has also released 14 new ringtones, ranging from soundtrack snippets to in-game sound effects. Odds are you could totally pick up some chicks (or dudes) with the Orange and Blue portal shooting noises as ringtones. That’s just science.
There’s really no reason why you shouldn’t download both soundtracks (both vol. 1 and the new vol. 2). To reiterate: they are completely free. There is nothing to lose here. So head on over to Valve’s official site and snag what you can before volume 3 drops.