It depends on your budget and expectations. For example for a HD 650 a headphone amp is a welcome addition.
I use oppo pm-2 with ha-1 (dac and headphone amp) streaming Tidal.
It sounds really nice but it costed me close to 2 grands....
Can you try now if possible? Any music video is fine give me the link please. I don't care if its not in English the music.Dont know cause never tried youtube on it.
Be aware though, many high end headphones will reveal every shortcoming of the record so a ****** source will sound really bad.
I use Cambridge Audio DacMagic Plus with AKG 701 connected via USB to my PC. For me the sound is great, specially when playing HD audio files. I am not sure if AKG 701 is any better than your Denon headphones.Thanks guys!
Is it worth getting a DAC and Headphone Amp too ?
I would not generalize. There is a lot of content in HD or even 4K with high audio quality. If you have fast connection, then you can enjoy nice sound.YouTube? Compressed beyond help,low resolution video,crappy sound.
I prefer to look up music videos (I guess it's those you're after,if sound quality matters) from Apple Music,generally better sound quality than YouTube.