yup went for 3 rounds of deliberations that lasted for maybe ~6hrs in total... cycling through ak120, ak100ii, ak120ii, ak240, x5 and zx1 (different combo on different occasions, not all daps each time).
long forgotten how the ak100 sounds.
ak100ii, 120ii and 240 are in the same signature family, with each model having better refinement and maybe separation/layering. i'm not really concerned about the single/dual dac thingy. for me i think the ak120ii is a rather pointless model that serves little purpose. the difference between the 3 is like.... ak100ii though not cheap, its built and aesthetics kinda made up for it, or at least most of it (and the rest is some extra carrot if you wanna think of it that way). still quite an accomplished player at that price point. not a heaven and earth difference from the 120ii, which makes it kinda boliao at double the price, where if you can afford the 120ii, imo should just bite the bullet go straight for the 240.
ak120 is still in a world of its own. the newer trio has the typical neutralish and slight brightish and airy sig. ak120 is warmer, darker and sounds more "studio". in some ways the trio may sound abit "digital" and the ak120 more "analogue". specifically between ak100ii and ak120 (which is my main interest), i think it's not a matter of which sounds better but rather down to sig preference. frankly i can live with either sig. detail wise i think they are pretty close. ak120's bass has more impact, but ak100ii's is slightly tighter and has better layering though leaner. since you have the 240, maybe can imagine the 100ii as a more blunt and loose 240
for me i would like to have the ak100ii as an alternative to ak120. size is not bad (lesser head tumor compared to the 120ii

), better looking casing (i dun like the croc-like skin of the 120ii), and sounds good enough to make the double-priced 120ii abit pointless.
as for zx1, i finally got to listen to my own songs. brought laptop to transfer. overall not bad but the bottom felt somewhat loose. can be a good bargain against the 100ii. however i don't really like the UI and the functions itself. many pple will like it la but what i'm looking for is a music player and that's it. the zx1 is too full featured lol. for simple and direct, the ak UI is still preferred.
x5 was one of the dap in all sessions. i would think its sig is closer to the cirrus-ed AKs than to the others. when i switched from ak100ii/120ii to x5, i always get the facepalm feeling. knn spend thousands on an ak but actually a sub 500 x5 would do the job so damn well. of cos certain aspects are still not there but it wasn't a win-all for the AKs either.
same goes for the zx1. the only gripe i have with x5 is the wheel.
ok abit disorganised impressions.... but agar agar get the idea i hope. conclusion is... status quo with ak120. again, it's in a world of its own

. when warranty expires end of the year and if up lorry after that, i might consider the ak100ii. x5 remains possible but always holding back due to UI. looking forward to x7 though.
disclaimer: above are all my imo and are quite disorganised due to the number of daps heard over a short time. any disagreement pls feel free. just dun shoot me.