Sadly IEMs only as I find headphones too sweaty in tropical countries like the Philippines. I used to have the AKG K712 and Schiit Asgard 2 as amp but switched to Yahama HS7/HS8S speakers and Schiit Saga as preamp setup because speakers provide the bass physicality I wanted as well as untouchable soundstage and imaging capability that they provide. Also, I get way too sweaty with the K712 with the velour pads on my face. Well, you can't really compare the soundstage and imaging of speakers against headphones. Anyways, I got into IEM world after interest of maximizing my portable audio or more specific, reaching the fidelity I get with the speaker setup by getting the CA Vega blind-bought. While I liked its holographic imaging, it literally cannot come close to the HS7 speakers in mids and treble tonality and detail retrieval. Then I got lucky with the sale CA Andromeda CK Blue edition, and that's where I experimented with budget DAPs until I landed with the iPod Touch 6G as my preferred DAP due to it sounding pretty close to the Yahama HS7 speakers in tonality with Andromeda being slightly warmer and slightly recessed in mids in comparison. Though if talking about neutral flat sound, I always refer to Yamaha HS7 as my reference.
Regarding other IEMs I've demoed, I always felt that they really need the extra power to sound the way they're intended. For example, the U12T and U18T sounded slightly flat and lacking punch with the iPod Touch but when driven with Chord Hugo 2, they sound incredibly full, wide, open and showing excellent layering, and maybe superior to the Andromeda that is also plugged into Hugo 2. As for DAC quality (Hugo 2 vs iPod Touch), Hugo 2 is definitely much more "blacker" where you perceive the instruments popping out of nothingness in a darker way than the iPod Touch. This is more apparent with more complex passages BTW. At least that's how I heard the Andromeda coming out of Hugo 2 + HMS setup. Also, mids and treble resonance are much more "separated" (not by width but by transients or speed as some people call it) I think it has to do with the much more accurate taps that is unique to Chord sound. Though I can easily get a better DAP than iPod Touch, I cannot live without Apple Music and the iPod Touch is the only DAP that has that capability (aside from smartphones) AFAIK