For the variax electrics you can adjust the volume of each string, that function may be available for the acoustic as well.  In addition, the was some sequence you could set at power up that would allow you to adjust the individual volumes from the guitar itself (I don't remeber what is was, check vettaville.com or vettaville.nl) for the electrics, again this may be available for the acoustic.

Sorry I just checked and the 300 acoustic will not work with the workbench

Here is a link from the institute of noise about the electric start up modes:

http://www.instituteofnoise.com/forum/topic.asp?TOPIC_ID=15539&SearchTerms=string,volume

Someone at line6 technical support may be able to tell you if there is a startup mode for your 300, give them a call.

Message was edited by: Khromagi

I had the same problem.  You might be able to correct the symptom by loosening all the strings.  As you re-tighten them, they tend to rock the saddle toward the neck.  Use your finger tips to pull the saddle away from the neck as hard as you can while tightening the strings.  Tune it a little sharp as you hold the saddle, then let go and tune it to pitch.  This worked for my Acoustic 300.  Once I did this and had the balance good, I could touch up tuning without recreating the problem.  It only seemed to happen when I changed strings.  Others have said it worked for them, but not for everyone.  Eventually, I took it to a Line 6 repair center just before the warranty ran out and they replaced the peizo pickup.  It's been fine since then.  I believe the pickups are made by LR Baggs.  Good luck.