@ozzy
I put together two new power cords about a week ago using Furutech FP-S55N with FI-50 NCF and FP-S032N with FI-28(R). Going thru almost exactly the same nasty break in as you are experiencing with Audioquest.
The minute I plugged the new power cord in the sound was incredible. Best I ever heard my system sound. Then 2 days in harsh, muffled, artificial, glare, boomy. Then there was no bass…gone…just harsh mids and highs.
I stopped listening and just gave it a 3 days with the components on 24/7.
Thankfully about 110-120hrs in it’s coming around. The delicate highs, clarity in mids and textured lively deep bass. I’m expecting it to settle around 200hr mark but continue to improve up to around 600hrs based on what I’m reading.
Break in is real and this was worse than anything I have ever heard during the break in phase.
Power Cable Break In - Such a Change!
I installed a new AudioQuest Dragon Source power cord from my Lumin X1 to my Niagara 7000. The power cord from the wall to the Niagara 7000 is also a Dragon but the High Current version. I bought that cord used.
So, when I first started using the new power cord everything sounded great. However, after a couple of days I started hearing a strident sound. Especially in the upper mid/ treble region. The bass was also constricted. I started blaming the sound change on another piece of equipment that was installed concurrently.
Now, I was under the impression that the Dragon power cord with its DBS system required no break in. But I did inquire about it to AudioQuest who responded that it would still need about 150 hours to break in. It's been close to that now and sure enough yesterday I started hearing the glorious sound that I heard from day one with the power cord only perhaps better.
I must say the difference during break in and now is quite remarkable, I don't remember any other power cord going through this amount of dramatic change.
ozzy