There could be a number of reasons why dialogue is difficult to hear.
1) a particularly reflective Room
2) a large room
3) a tweeter with poor off-axis performance
4) low SNR pre-amp
I assume this is not a TV sitting on your desk and you are actually sitting away from it at some distance. #3 and #4 will definitely affect your ability to hear vocals. I've heard the ifi and it's fantastic, but they are a pair of multimedia speakers so compared to typical stereo/ht speakers their performance suffers quite a bit from bad off-axis performance and a noisy pre-amp. If this is in a office-sized room, then #1 (and #2) is unlikely.
So a few questions:
1) How big is a the room
2) How far away do you sit from your TV?
3) How far away are the speakers from you?