Guitar and amp issues?

ClintBarton In Guitares | Posted 4 years ago
I have a marshall jcm900 amplifier with recording compensation on the back and direct line out, when i play my guitar with usb direct to audacity its fine and a clear recording, but when i run it through my jcm stack i get a high pitched scream whilst recording ,you can still hear the guitar , , iv twiddled with everything trying to stop it but no joy,my other problem is the delay that comes with playing and recording? is there anyway to remove the delay? thanx any helps appreciated.
Please help.
I did not find the right solution from the Internet.
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