I've come to enjoy the PCM-1704. I have a Resolution Audio Opus 21 and Lessloss DAC 2004 MkII that use this chip.
Yes, I've heard these products, including Opus 21 modified by a respected company. Both Lessloss and Opus 21 sound quite nice at their price-points. Unfortunately, I still hear the effect in the midrange and upper octaves I mentioned in my previous post.
Furthermore, I am very happy that Esoteric moved away from PCM1704 and now uses AKM (AK4399) in their latest reference players.
I do not hear the same problem with TDA1541.
Best,
Alex Peychev