Access Virus TI Snow latency in Ableton 9 + Motu Ultralite MK III

  • Hi everybody. I've just bought an Access Virus TI Snow and I really like its sounds.
    Unfortunately I have a big problem with latency. I use it as VST inside Ableton Live 9 and I control it with my master keyboard (an Arturia Factory Keyboard).
    I'm working with 256 buffer and high quality.
    My soundcard is a MOTU Ultralite MK III and my laptop is a Mac Book Pro quad core i7 - 8Gb Ram.
    I've read somewhere that to avoid this problem I should use the Snow as main soundcard but in this way I couldn't use my MOTU, and I need it for my music.
    Can I use both of them as soundcard?
    Is there anyone who has had the same problem and has solved it?
    Please help me if you can because I'm really in trouble...


    P.S: sorry for my English ^^