denon = marantz = onkyo
When it comes to the headphone outs on hifi gear not primarily designed for headphones
, the variation is massive, some are terrible, some are half way decent. Very occasionally a headphone out might be exceptionally good (high end preamps mostly). Usually the headphone out is just a cheap circuit thrown in there. Quality is on average about the same as a PMP but a bit more power.
And there is not a lot of correlation between quality of headphone stage to quality of brand, or even price of product.
So in other words you'd need to try it and see.
Also, this denon must "have a built in dac". Anything that accepts digital inputs and outputs analogue must have a DAC(D
onvertor) inside. As for how good it's internal dac is, nfi.
My 2c when it comes to the MS1. These heaphones don't respond massively to better source/amp IME. They sound great from an iphone, but don't get a whole lot better than that. I tried them with a good source and amp and this just made it obvious that the headphones were the "weak link in the chain".
However, this might be a slightly harsh judgement as when i was using them with my iphone i was just listening to music and enjoying it. When i had it hooked up to my good system, i was in an analytical frame of mind so was basically listening for flaws, which were easy to hear on good gear.