Headphones

As the title says.

I've a small collection of headphones, none are difficult to drive, have three Beyerdynamics, of which I only use one often, and my mostly used currently would be the Hifiman 4xx.

Very happy with the sound I get out of them at about 50% volume on the Zen Air DAC (tried the Zen DAC 2 at first and then the Air and didn't hear any difference between them to justify the €100 premium) but recently I've been wondering if it would be worth it to add the Zen Air Can to the setup and thus, getting a nice little iFi stack going.

On paper, the Zen Air Can would add plenty of power and a "balanced" output but would it be worth it, would I be getting anything of value ? And is Xspace worth it ? Haven't found much being said online about it, at least not enough to form an opinion.

Please do keep in mind I am not really interested in other amps and I've limited myself to €100, which is the price of both the Zen Air DAC and the Zen Air Can.