Feedback Destroyer?...

[MOFO Pro]

Your guitarist play a hollow body?

 

[VESSEL2020]

Your guitarist play a hollow body?

Nope,..Jackson Professional Flying V
with active EMG 85 pickup.

 

[ocnor]

The SPX50D is overdriving the shit out of the amps inputs and that's why you have feedback. Since you favor the SPX distortion try hooking it up this way:

guitar > Metalcore > NS-1 > Mesa input [clean channel] > Mesa effects send > SPX50D input > SPX L+R outputs > Mesa + 5150 effects returns [Left to one amp Right to the other]

OR

guitar > Metalcore > NS-1 > 5150 input > 5150 effects send > SPX50D input > SPX L+R outputs > Mesa + 5150 effects returns [Left to one amp Right to the other]

 

[VESSEL2020]

The SPX50D is overdriving the shit out of the amps inputs and that's why you have feedback. Since you favor the SPX distortion try hooking it up this way:

guitar > Metalcore > NS-1 > Mesa input [clean channel] > Mesa effects send > SPX50D input > SPX L+R outputs > Mesa + 5150 effects returns [Left to one amp Right to the other]

OR

guitar > Metalcore > NS-1 > 5150 input > 5150 effects send > SPX50D input > SPX L+R outputs > Mesa + 5150 effects returns [Left to one amp Right to the other]

Those are some very good suggestions,..and I believe that is the one way we haven't tried it yet.
(Left output to one amp and right output to the other) because of the a/b already splitting them.
Thanks for the suggestions,...gonna try 'em out on Monday, and I'll get back to you with the results.

 

[VESSEL2020]

The SPX50D is overdriving the shit out of the amps inputs and that's why you have feedback. Since you favor the SPX distortion try hooking it up this way:

guitar > Metalcore > NS-1 > Mesa input [clean channel] > Mesa effects send > SPX50D input > SPX L+R outputs > Mesa + 5150 effects returns [Left to one amp Right to the other]

OR

guitar > Metalcore > NS-1 > 5150 input > 5150 effects send > SPX50D input > SPX L+R outputs > Mesa + 5150 effects returns [Left to one amp Right to the other]

I am very happy to report,...This ^ suggestion worked.
No more feedback.
Thank you ocnor.