Hi, I’m Louie. Sorry you had to wait awhile but I’ll do my best to help.
Initially, have you tried the Pioneer with no speaker/wires connected?
And have you tried a RESET of the SC-27?
Consider a RESET. A reset is both a test and a try of a fix. As it implies, a reset would force the unit to revert back to factory defaults removing glitches and config errors but would include memories, presets and user preferences. After a reset, the initial setup would have to be performed. If have not been done and should you venture to try: Please click HERE.
May have to be done a number of times.
This is very critical - a reset however would not be corrective of an internal hardware concern; but it would be confirmed. In some instances, it may even expose/cause other issues.
Then it would appear to be an internal hardware issue.
The above was the safe user's RESET.
There is another; a technician's RESET. This procedure is also an attempt of a fix and a test. However, the test is 2-edge tool. it either identifies the fault and/or it allows the fault to manifest itself (sometimes burning) as the protection circuitry is bypassed.
Would you be comfortable giving the technician's RESET a try?
As posted above, it either fixes or it allows it to burn....or nothing.