Dragonfly Red or...$200 or under.
So I'm new to the whole dac/amp scene so I'm sure I could use some direction here. I recently purchased two headphones, the sennheiser 58x and the hifiman4xx. My choices originally were between the DFR or nextdrive spectra X but based off reviews I went and bought the DFR but will return it if need be. I generally will be doing all of my listening through my phone which is the Samsung Galaxy note 10 plus which needs a USB C connection. The form factor is what really pulled me in but quality is obviously the most important aspect so if theirs a good all around dac/amp that can be used on my phone and computer that's a bigger form factor that's fine too, while also powering both of these headphones correctly. So what would you guys recommend?

May 5, 2020
If you want to stick to mobile listening, just stick with what you have and press the 'ignore' button on everything else. The reality is that the DFR is limited in its capabilities (it's good for what it is), and putting an amp afterwards is pointless because there's no way to bypass the built-in amp.
May 4, 2020
I also went with the DFR to go with my HIFIMAN HE400S. The DFR has been very well reviewed not only by headphone sites but also by the big audio mags where it was used in their big systems as well as with ‘phones, and it acquitted itself well on all accounts even compared to some accomplished and much pricier standalone DACs. I think that’s a tough test and says a lot about the level of the DFR’s performance capabilities. I found the DFR immediately expanded the soundstage and improved imaging/dynamics and in general provided a much more enjoyable “out of the head” listening experience versus being plugged directly into my iPhone, which sounded collapsed, congested, and just flat by comparison. Bottom line — I think you’d need to spend more to get a meaningfully superior experience to the DFR, and the fact that the DFR is so easy to take on the go is a very nice bonus IME. In the future I will experiment with separate amps and tube DACs, but I’m in no rush given the sound quality I’m enjoying now, and I think you made a good choice. For the 58x I’d be tempted to try a Cavalli CTH amp in conjunction with the DFR as it seems to synergize exceptionally well with Senns although may not do much to improve the 4xx, which doesn’t seem to scale as much with better amps. Anyway, just some thoughts and hope this helps somewhat.