Audient ID22 vs Apollo & update on
Based upon advice from another user out on the web, I bought a regulated 12v power supply to use instead of the little wall wart supplied by Universal Audio. It brings an already brilliant performer to the next level, and the cost is peanuts for what you get in return. For those willing to experiment, I got the power supply on Amazon:
Philmore Multi-Voltage Regulated DC Power Supply : MW122A
I had another cheap wall wart supply with the correct sized plug for the Apollo that was not being used for anything. if you do not have a sacrificial lamb for the connector, you could use one like this from Amazon:
Velleman PSSMV1USA 3-12Vdc Switching Power Supply
I cut off the wire from the wall wart, stripped the wires and attached them to the regulated supply binding posts. You will need a little volt/ohm meter to make sure that you have positive on the center contact, negative on the outer shell. I also measured the power supply to be sure that it was in spec. My specimen measured at 11.83 volts. The original wall wart for the Apollo measured 12.30, but that was not under load.
This particular power supply (Philmore) is very nice because there is a switch that locks the voltage so that it does not change by accident. (Be sure to set the switch to 12v) It provides a very solid 2 amp capacity, and by the weight of it, it feels like a true transformer with regulation, not a little switching supply.
For those of you who may own an Audient ID22 or are thinking about getting one; The power supply suggestion above works even better on my Audient ID22. It is not surprising that there would be wide differences in the quality of wall wart power units and this simple, inexpensive upgrade brings the Audient into very close competition, sound quality wise, with the Apollo. I needed a good USB isolator for the Audient. You may not need one, but you won't know until you try.
Audient ID22 vs Apollo Twin Duo USB (sound quality of the headphone outputs):
The Audient with the new regulated power supply is, to my ears, in the same ball park as the Apollo with the new regulated power supply. They do have a different signature. The Audient comes across with a warmer sound, while the Apollo is more neutral. On the Beyerdynamic 1770 headphones, I was hard pressed to declare a winner. Every time I thought I heard more detail on the Apollo, I switch back to the Audient and there it was, just a little warmer. It comes down more to taste. Perhaps the most telling result of my testing so far is that I am keeping both units. The Apollo does a whole lot more, but costs $300 more and requires USB 3.0, while the Audient works nicely on USB 2.0.
If you have an ID22 and are looking to upgrade the sound quality, get the new regulated power supply. No need to sell off the Audient to purchase the Apollo, unless you want all the new capability of the Apollo, such as 192khz, DSP features, etc.
I am completely thrilled with the sound quality of both units after the power supply upgrade (and USB isolation on the Audient in my setup, you may not need one). Your mileage may vary.