Is there any such thing as a bad sounding DAC these days?

The digital part is thoroughly transparent, always. The only thing that matters is the analog output, and that's where we measure the transparency (or not) of a DAC. Of course there could be some sort of contamination (as with everything analog), but it would be captured in measurements. DACs imo have been a thoroughly solved problem for a long time. It's not where I'd want to tune my system to have a signature... amp and speakers... sure. I am not saying I believe utter transparency should be everybody's ideal. :-)

You might be surprised by hearing some very nice sounding DACs / players from long ago. They will absolutely measure like dog crap compared to modern. But our ear-brains do not process information via Fast Fourier Transform!

Perhaps surprisingly, our ears and brain DO process sound almost exactly like a Fast Fourier Transform.

Our cochlea and our auditory cortex are tonotopic.  When a complex wave gets to our inner ear, different frequencies within the complex wave have peak resonant points at different physical locations along the basilar membranes of our cochlea which have different stereocilia bundles connected to them. Our inner ear actually breaks down the complex wave into component frequencies based on where each component frequency maximally excites the basilar membrane, and we have separate nerve firings for each of those component frequencies based on the hair cell bundles connected to the basilar membrane at those locations. The tonotopic geography continues into the auditory cortex in the brain, which Dr. Nina Kraus of Northwestern likens to a piano, where you see different physical regions in the auditory cortex responding to different frequency components of the complex waveform.

So, yeah, actually, our ears and our brains are breaking down incoming complex waveforms into their component frequencies very much like an FFT, and, further, actually converting them into binary-like neural spikes -- when a stereocilia bundle is deflected it creates a nerve spike or no spike, functionally like a 1 or a 0 -- and those go up to higher centers of our brains where the physical separation continues until other processes take place to create a perception of an integrated sound (or multiple separate sounds).

It's a sidebar to matter of what people prefer in terms of the particular sound of a particular piece of equipment. But our ears and are brains, when we hear, are very much doing something very like an FFT.

Thanks @stuartk 

I did hear that shiny new DAC calling out to me.😃

@chervokas 

Thanks, very interesting, I did not know that.

our ears and our brains are breaking down incoming complex waveforms into their component frequencies very much like an FFT, and, further, actually converting them into binary-like neural spikes -- when a stereocilia bundle is deflected it creates a nerve spike or no spike, functionally like a 1 or a 0

So, if I'm reading you correctly you are saying that our brains re-convert (analog) sound waves into digital?

FFT is a mathematical transformation from time to frequency domain. Our ears respond to frequencies over time. The details of how they do that is a whole different story.  chervokas  seems to have a good handle on it.