If you are referring to the positive and negative speaker cables I checked and they are correct. It has been suggested I go with a power amp vs. this Roksan integrated streaming amp. I may go down that rabbit hole.
When you are using an integrated amp for this application (running front preouts from a receiver to such an amp), you would want it to have "power amp direct input" or equivalent connection, as can be found in the Marantz PM8006, Yamaha AS-1200, etc. This poweramp direct connection lets you remove the integrated amp's preamp sections from the chain when pairing with a receiver or prepro. Hence, you can also use it as a standalone integ amp and it would also be ideal for multitasking the way you want it to a.k.a as a 2 channel integ amp and and as a poweramp in a multichannel 5.1 application.
Your Roksan could work (less optimal however) as long as you find a set sweet spot for its volume knob and re-run your receiver's calibration for your multichannel application. But, it currently looks like your amp may have a defect (imbalanced channel levels or something) that your receiver is correcting for, which is why i suggested that you
troubleshoot the amp on its own first in a stereo application (completely remove the receiver from the picture, do a factory reset, etc). It is supposed to be a standalone stereo amp with streaming features, isn't it?
Good luck.