@dbb Very good choice to keep! I guess I couldn't understand your choice vs keeping 005 since I hear the 006 as more forgiving and natural. Sorry to learn of your hearing loss, not unusual to lose the ability to hear highs, I can only hear up to 16khz in a very quiet environment. In a noisier environment this more severely impacted. I won't go much into this, but we often don't realize how much the background or ambient noise levels of our listening rooms impacts our ability to hear certain frequencies, these ambient noise levels may completely mask certain frequencies in general, and actually change the mix to some degree on our recordings. I choose to exclusively listen at night when ambient noise levels at naturally lower due to the outside world slowing down. I even tried Schumann resonators, won't go into that.
Again, it may well be the particular presentation of the 006 doesn't suit you, after hearing the Harmony in my system I can understand the appeal of that presentation. In thinking about this I recall my audio show attending days, I'd often go into rooms where there were relatively low resolving systems but musical and inviting. Many would congregate to these rooms, I was always seeking the highest resolving rooms, yes, some could be irritating, but once in a while I heard high resolution along with those inviting qualities in the lower resolving rooms. And this was some years ago, so digital not nearly the quality of today, You can take a dac like the Harmony, enough resolving ability to be involving, yet be entirely musical. I suspect a Harmony magically placed in any of those rooms may have been best of show for me, that's how far digital has come. Point is 006 simply not needed anymore for many, this for the resolution seekers, and you must already have a highly resolving system in place to hear it's full potential. Without that simply wasting your money, although I consider 006 to be amazing value at $3900! I'd also reiterate 006 should sound nice in virtually any system, relatively natural timbre and neutral tonal balance should ensure that.