MacBook Pro Playback distortion

Hello everyone.  I have a computer / server question.  I have an Apple MacBook Pro, 500 GB SSD drive, and 16 gb RAM running under Mojave.  The computer is 98 % used for music, and I placed about 500 CD’s on the drive in AIFF format.  Did this abt 4 months ago, and life has kept me from really listening , until recently. To my surprise , I have a just awful distortion in the playback when using the computer  ??  Low end is actually distorted, and the mids and highs are all off base.  I have took the system down, and worked my way back, starting with just the power amp and an old IPOD Classic ( spinning drive model ) driving the amp directly.  Re-added each part of the system ( with NO, issues ), until I got back to the Apple Computer.  Odd thing is I don’t have the problem when using the computer for on line streaming,  just ITunes when playing back the AIFF copies of the CD’s.

I think I have the I Tunes playback set-up correctly, but maybe not.