Yes it will be and a big one, I made the jump 3 weeks ago and never looked back, I am stunned at how good the WM1A is and that's singled ended WM1A vs DP-X1 balanced! Also that's volume capped WM1A vs japanese version of DP-X1.
The WM1A is full bodied, timbre and texture are just simply miles beter in my book and the layers and layers of depth...
I never liked DP-X1 from the beginning. I am very open minded, and as far as this hobby go, I do realize that there is the different between more analog sounding (tube like) or digital sounding (solid states). Of course in each signatures, there are bad and there are worse, then there is something of good quality. IMO, DP-X1 was not good for digital type of sounding, the Opus 2 is ways better. The Zx2 is good for more analog tuned signatures, but it power is low, and it lacks some resolutions at the lower trebles with the back ground not as clean. So, no doubt the 1A sounds much better, supposedly it is the alternative version of 1Z.
I would say if someone love the sound of Zx2 and want an upgrade, the 1A is definitely it successor and is on par with Pha-3 just as much as 1Z in balanced mode. However, if someone is seeking that extra warmth and tubes like ? The 1Z will have that. Expensive, of course, but if it requires no stacking ? Why not. The only downside is that neither 1A or 1Z can be used as External DAC. Under this situation, I would call 1A being tremendous value in comparison the 1Z, the 1A prices is just as much as Zx2 as you get more audio dedicated performances, you lose the wifi and android capability.....1Z is still priced too high IMO for what it offers, it performances is no doubt top tier (preferences aside), but 1Z is only aiming toward those who either want to be at the top of the productions line, or enjoy the ability of it luxury or both. In the end, people can chose to buy a High Lander from Toyota or an Rx350 from Lexus
Also, to those who had been wondering, the engineers from Sony states that 1A is Zx2 direct successor but the company had chosen to stick with Walkman Os instead for better battery, upgradability, and sound performances, and so the name is WM and no longer ZX. Knowing Sony, Zx2 is probably the last of it ZX line with android OS. They also states that the 1A is approaching the Solid states signature as oppose to 1Z which is toward the Tube warmth. There, you have it