OK good, so now at least we have some context. You're comparing the AK380 amp with the ALO Mk3B and the headphones in scope is the LCD2. That's fair enough. I would think that there's probably a selection of
portable amps that can and a selection that can't drive the LCD2 - and by drive, I mean just raw power drive, but not necessarily drive
well. To me, with most of the Audeze LCD range, they would probably benefit from a desktop level amp to drive them to their full potential.
Anyhow, I don't think that makes the AK380 amp a poor amp just because it can't drive the LCD2 - that is a rather demanding headphone. Similarly with some of the earlier Hifiman headphones. However the AK380 amp drives plenty of other headphones and do so reasonably well. I didn't have any issues with the AK380 amp driving the HE1k, HD800S, HD800, and Ethers (although I didn't really try listening to the Ethers for more than just a few minutes). I actually intend for the AK380Cu/Amp to drive the HD800S once I work out how to get 2.5mm TRRS balanced HD800S cables (no Paypal for me, so that's where the challenge is), as I have tried it in the shops already and am satisfied with it. Hopefully I'll get my AK380 Cu Amp from FedEx tomorrow or Monday.