I personally think about it in the categories of source, dac/amp, and pure amp, so thats how I will list it. Here are the items I would look into as TOTL in no real order (sorry if I miss some, please feel free to add yall)
Source:
- Sony DMP-Z1
- Luxury & Precision P6 Pro
- Luxury & Precision LP6 Ti
- Lotoo LPGT (and Ti)
- AK SP2000
- Chord Hugo2go combo
- Hifiman HM1000
Dac/Amp (you need a source)
- Diablo
- Hugo2 (without 2go)
- YinLiMev M400 Pro
- Honey H1
Pure Amp
- Cayin C9
- LessFox BX2 Plus
- Bakoon HPA-01M
- Mass Kobo 404/424/428 (all basically the same amp with different wrappers)
- Phatlabs Phantasy II
- Woo Audio WA8
- Woo Audio WA11 (though the general impression of this one doesn't seem particularly positive)
- XiAudio Broadway (battery powered, so I included it, but imo too big to really count)
Honestly, I am positive im missing some stuff in the amp section. There are just too many ones that are rarely talked about to keep track of tbh.
Here is my take as a portable only listener:
Hugo 2 has long been touted at the absolute peak of portable dacs/dacamps. The P6 Pro, while quite different in presentation, fully competes with it and my preference for one over the other is 100% down to synergy of the can (for example mest on P6P are legitimate end game for me while mest on H2 I wouldnt even keep them. It is visa versa for Clears). If you are not squeamish about the pricing here, the sources I would realy look into are the Hugo 2, P6 Pro, LP6Ti, and LPGT (and possibly Ti if you will only rarely use a portable amp but want to drive more demanding over ears). All of these are really fantastic places to start and make for great AOI devices. Once you feel settled here, then start looking into amp pairing. Unfortunately there arent a ton of people with a lot of portable amp experience, but thy can be found if you lurk in enough threads
EDIT: Just for context, I have the P6P, H2Go, Micro BL (which I mostly use as an amp), 428 (just got it this weekend, so no opinion on it yet), and Honey H1.