I had the Zen Signature v2 and the Zen DAC v2 before I upgraded to the Gustard x26 pro. Personally, I liked the Zen DAC v2 better than the Signature because it has the TrueBass and PowerMatch options that will pass through to your amp if you run the unit in variable volume output mode, whereas the Signature is pretty bare bones and uses essentially the same Burr Brown chipset.i got the Zen Stream to work again last night after i did a factory re-set. it sounded great running into my old Nad D1050, but crashed a couple of times. annoying, up to its same old tricks. i think its a hair better than the 2i, but the Node 2i is stable. in Thailand they speak very little English and the ISP had no clue what a multi cast was? i wanted them to come out and change the setting. but since the 2i well come soon i will use this as a back up.. i am a fan of the Burr-Brown chips that are used in the 2i. i may buy a Zen Signature V2 which uses the same chip to partner with the Zen Stream or 2i? have you heard the V2? what are you using?
In either configuration the addition of a Zen CAN (which has xBass and xSpace options to add to the sound signature options on the Zen DAC v2) or a Zen CAN Signature (which comes in two varieties to mimic Hifiman or Sennheiser 6xx tonality, the latter of which I vastly prefer) makes a huge difference, as does buying a 5V iPower X power supply. And I would also strongly suggest getting the 15V iPower X for the ZS, which adds higher amperage, more clean headroom and better Wi-Fi stability over the stock wall wart. And the sound is significantly improved by turning off the internal mixer altogether and use your DAC for all volume settings.
Final hint: link to the ZS developer GUI at iFi.local/dev. This allows you to access beta firmware and see a lot of data under the hood. Turning on the beta firmware option otherwise changes nothing in functionality; simply go back to iFi.local to get back the original GUI.