Hi all,\n\nI’ve read through this thread with great interest, and posted a question in the main forum yesterday, but I think I need the advice of you lot, as so far the only thing I’ve been told is Audyssey is garbage and I shouldn’t use it\n\n\nI have an issue (on both the Marantz 6012 and Denon 3500H) where I get a constant bass distortion from my left speaker when using Audyssey with my external DAC. I’m running it into the CD input RCAs. On both receivers!\n\nI figured it was a line level input issue, but even after setting the source input to -10db the distortion remains. Also, if I use Airplay or other digital inputs the distortion isn’t present\n\nTo make things even weirder, when I run the DAC in “pure direct” mode there is no distortion, even at incredibly high SPLs.\n\nI’ve attached a photo of my room correction results.\n\nI’m running a Marantz SR6012 into two NAD 2400thx power amps, driving my NHT Classic Four speakers, being aided by two Infinity Sub R12s. The external DAC is the D1+ tube DAC from Maverick Audio.\n\nthe distortion is present even with “L\/R bypass” or Flat is selected, which makes no sense. I’ve also attached my levels post calibration.\n\n\nFrom the screenshots you posted I see no reason for the distortions to be Audyssey related. You said no distortions in pure direct, but have you tried Audyssey off (I know you tried bypass already). When on pure direct, did you play exactly the same content, and play it long enough just to be sure? And same for direct, and stereo with Audyssey set to "off"?\n\nIf you are 100% sure that the distortion is only audible from the left channel and that the speaker is not the problem (proved by swapping the left\/right interconnects), and only when Audyssey on then I would say it has to be the DAC. What's the model number of the DAC?