[blueTab]

Not too long ago I purchased a used Matrix M-Stage HPA-1 (without USB) but upon plugging everything in there appears to be major problems. The seller tells me it was in perfect condition and was checked before shipping and they have perfect feedback so I'm inclined to believe them so I would like to troubleshoot the issue before I send it back to the seller or to Matrix for repairs.
 
The issue I’m having with the M-Stage is that plugging RCA cables into Input 1 produces no sound at all (no matter what I select on the front) and plugging the RCA cables into Input 2 produces heavily distorted sound that plays the same no matter which input I select on the front of the device. I've tried different RCA cables, different input sources, and even different impedance headphones. I even swapped out the op-amp chip and checked the fuse and still same issue. Inside the device looks in perfect condition, no obvious signs of an electrical short or any physical trauma to the device. The device was also well packaged.
 
If you are familiar with the M-Stage it might help to know that on the board LED2 lights up but LED3 does not.
 
Is there anything else I should try to troubleshoot this?
 
Thanks!

 

[PleasantSounds]

From what you are describing this is not how properly working amp would behave. 
If I were you I'd send it back to the seller.