Synching loops

Question

Hi all, I have a difficulty in getting loops to synch, I'll try to describe the problem as best I can.
I have a finished song in Logic 9. One of the tracks contains a drum loop. This is created using one of the sample loops I dragged onto the arrange window from one of the jam packs. It's midi info not an audio file. It triggers "Drum kits" which can be found under Garage Band instruments/Drum Kits/Stero. It automatically synchs to my song tempo great and works perfectly.
When I come to play this song live, one of my band members uses a drum pad (Yamaha DTXpress) and I've configured mainstage successfully so that, when he strikes his pad the loop plays back. I did this by soloing my track in logic that contains the drum loop, setting the selection area for exactly 2 bars (the length of the loop) and bouncing down a Aiff file. I then create a new track in mainstage, set the playback plug in on it, feed the playback pluging my 2 bar aif file I bounced earlier. Then assigned the pad to play the start button of the playback plug in. When I strike my pad - hey presto, I hear my perfect 2 bar loop! It's exactly cut because when I strike my pad, I can hear a bass drum hit that occurs right at the start of the audio file.
All seems well, but when trying to play along with the band, the strike on the pad is bang on time, but the loop plays approx half a beat too late and is almost impossible to get in time because of this. It's not a tempo issue as both logic and mainstage are set to 152 BPM (my song tempo).
If I didn't know better, I'd say it was our old enemy latency. But this doesn't add up to me because if the playback function had bad latency issues, it renders it almost useless - I must be doing something wrong?
Any ideas?
Is setting my loop audio file to play using the playback plug in the best way to go about triggering my drum loop?
One other thing to add - If I set playback to start at the next beat or at the start of the next bar, it all works fine and plays in time. This isn't a very intuitive way to play a live drum loop though - surely you want to smack the pad right on the nose of the beat? Rather than before it a short while.
Sorry for the long message but I kinda hate those posts where people don't explain their problem exactly! lol.
I'm using Logic 9 and mainstage 2. I have a white mac laptop: 4 gig of SDRAM and I'm on mac OSX version 10.6.2.
HUGE thanks to anyone who can either tell me what I'm doing wrong or suggest a better way of getting an audio file loop to play instantly and in time with the rest of the band!
Cheers all.
Meady200.

Answer 1

Thanks so much for your reply. I'll give that a go and report back my findings.
So, I guess this is a latency issue after all. That's a bit rubbish. I don't understand why my sample can't load into RAM and be instantly triggered. Perhaps Playback streams off the hard drive because it's designed for larger files ...Which then makes me think the two solutions you suggest may work because they probably do load the files into RAM. Sweet!
I'll try it after work.
Cheers.