I've just discovered that the iFi iPower that comes with their new Zen-Can amp for ($20)extra actually makes the amp sound worse compared to an old 5v adapter I use for another device . I had plugged it into the Zen-Can amp by mistake and couldn't understand why I was really enjoying music more than usual for about 2 weeks. Now when I switch back and fort between the two 5v adapters I can pinpoint the difference. The iFi iPower supply makes the music sound more compressed, basically clarity and detail are worse. The end result is you feel like you're not enjoying music as much.
The Zen-Amp itself really does sound excellent, it's really very engaging with music.
I believe they had issues with the iPower adapters in the past but how can they be still be upselling an add-on "Clean" power supply that reduces the performance of their really good amp. As @
amirm has said in the past relating to snake-oil, it's one thing to sell a product that does absolutely nothing to improve audio quality - but they are selling something that makes their audio equipment sound worse!
iFi are now selling the newer $100 iPowerX - I hope they're not unloading their older (defective) $50 iPower to new purchasers of the Zen-Can amp which for many will be their first Class-A amp and will be just happy with all the extra power and will not notice that the amp can sound a lot better with a properly functioning $8 power supply.
@GMG by the way it doesn't appear to affect my DAC, or at least it's not audible but it definitely affects the sound detail of the Class-A amp.
(Linksys 5v,2A) (iPower 5v,2.5A)