hiya
im using g4 733 mbox and pro tools LE at 6.4 but being honest I find it best to use mic'd up amps to record.
occasionally I find Protools hangs (cpu) after many plugins for about 10 tracks - so Im upgrading to to g5 1.8mhtz.
Tell about the line 6 hows that working for you ? might give one a go if
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John