How do I connect two speakers to my computer which have two balanced inputs: TRS and XLR and one unbalanced input: RCA?
Which input would be optimal for sound quality if there is any distinction between them? What is the difference between balanced and unbalanced inputs? These are the speakers: KRK Rokit RP10-3.
Can I also connect a subwoofer which has balanced XLR for left and right inputs to the same computer? This is the subwoofer: KRK 12sH0
So three speakers all up: two monitors and one subwoofer. From what I've read I would need an audio interface to connect all the speakers and then connect the interface to the computer. But I don't know what an interface is (a soundcard or mixer?).
Also are there any monitors or speakers which are better than the KRK ones listed above? For example would two Audioengine 5+ speakers and one Audioengine S8 be better?
The audio setup is for gaming and music (electronic, dubstep, DnB, dance). Quality low frequency response is desired most of all.
unbalanced is a analog audio signal carried by one wire.
balanced is two wires where one is carrying the signal and the other one carrying the inverted signal.
The point of balanced audio is that you can effectively filter out all noise picked up on the cables.
( signal +noise -(invertedsignal +noise) ) / 2 = (clean signal without noise)
Unless you have a large distance and noisy environment between your computer and speaker i don't think there is much benefit to the balanced solution. Unbalanced would work just as fine in this case.
In any case, you would need a audio interface with whatever connections you need to connect subwoofer and speakers to your system. A audio interface is basically just hardware that provides the connectivity and A/D converters you need. Unless of course if you choose to use the unbalanced RCA jack. Then you can just buy a standard TRS 3,5mm to 2x RCA and plug it in to your soundcard of choice. I'm assuming your speakers are powered.
You need an audio interface. It's a soundcard usually connected via USB or firewire with all your inputs, outputs, volume controls and has a software mixer/router. I would suggest the JBL LSR or Yamaha HS series (preferable HS8) over KRK though. KRK's have a muffled low end. Here is a video that helps you hear what the sound signature of each monitor sounds like.
https://www.youtube.com/watch?v=riXAOTRdTNA
A sub with those KRK's you want would likely be overkill. Audio engineers often don't use subs unless working on movies. I actually have a KRK sub that I really don't like. I don't use it when mixing (I use Yamaha HS80m's). Buy a sub later if you need more rumbles and explosions in video games. For music, you'll never need a sub with full range monitors unless you really want exaggerated low end.
Usually the recommendation is to use balanced if possible. I'm just saying it wouldn't be required in this case.
Regarding the TRS and XLR, Since they are both balanced inputs there is no difference other than the shape of the connector.
A sound card and an interface is basically the same thing as far as I know. Many times functionality of a mixer and interface overlap. It depends on the features of the particular product. Here is a good read on the difference between audio interfaces and mixers : http://www.gearslutz.com/board/electronic-music-instruments-electronic-music-production/648032-difference-between-mixer-audio-interface.html
I recommend a interface with the feature to route and mix audio. I have a RME Babyface and I find the included mix software super useful!