@mdrone I highly doubt all r2r dacs do this, and I've never experienced this on the AMT, but not sure exactly what you are describing is the same as how I'm interpreting it.
i.e. I can play some complex electronica, daft punk, etc and I don't feel It gets muddy or noisy
in fact there is a review on the Holo May DAC by goldensound where he specifically calls out how well it handles some complex music.