Melch - you need to rethink what you think you know!
first, the focusrite 2i2 "audio interface" IS a soundcard and you should never use your computer soundcard for your output when you have a real recording soundcard like the 2i2.
second, you CAN adjust the latency with the 2i2!
when you say you downloaded the software for the scarlett but couldn't get it to work - what exactly happened? which OS are you using?
this is going to be the key to getting your system working correctly. you need to get the scarlett software loaded and working on your computer. if you are downloading the correct version for your OS and it won't run, you need to contact focusrite tech support. they are really good with helping. they helped me and I didn't even ask them! they asked me first!
once you get that software running, you need to plug your speakers into the scarlett's output, or use headphones for monitoring, do NOT use the computer speakers on the computer soundcard for output. that way you'll be using TWO soundcards which have different clocks. you'll never be able to keep your tracks sync'd correctly that way. use the same soundcard (the scarlett) for both input and output.
once you have the scarlett software working, in MC, go to preferences ("p" on the computer keyboard) and go to playback and recording. then change the DRIVER MODE to ASIO.
then go to driver settings and verify that the scarlett is listed in both the RECORDING and PLAYBACK TIMING MASTER.
then click on the ASIO PANEL button on that tab. that will bring up your focusrite scarlett software. this is where you can change the latency. the lower the latency the faster the response between you MIDI keyboard and the softsynth you're using in MC. but it might also cause glitching, stuttering at very low latencies depending on your system. you might have to choose something a little higher. keep adjusting it until you find something that works with your system.