help...distortion (the bad kind)

ok…here’s the setup and problem…

Yamaha 16/4 mixer (1/4" mono out to 1/8" stereo line in on soundcards)
XP - P3 933, 512 Megs RAM
2 SB Live cards, connected via the AUD_Ext SPDIF connections
KX drivers
N-Track 3.x

We just set this up, and tried a test recording with the guitar amp using some mics. With the mic pre’s to -10, the track faders to -5, and the master to 0, the wave files look small (take up about half the height of the track at the peaks), but on playback the tracks (2 of them) will clip the master and sound distorted all-around. if you turn any of the mixer settings any higher, it just gets worse.

It seems to be a recording issue, as importing an old set of wave tracks (guitar L and R on two channels that was recorded last year using the same mics) that sits about 75% the height of the track will not distort or clip on playback.

Any help is appreciated