Pros: Integration with Apple Devices, SQ, well built, long battery life
Cons: Heavy, a bit large for a true "mobile" device, high noise floor, doesn't isolate RF from cell phone
So this will be a short and sweet review of the Theorem 720 of which I had for about 30 days and then had to return to Cypher Labs. My primary use for this device was to have something for listening to ALAC from my iPhone when I was at work or on the go. I was primarily feeding the output to my JH-16 pros with a balanced cable.
Pros: In short the integration with any apple device plus the ability to charge your iphone while playing music is awesome. If using the Theorem from your laptop the battery life is incredible. The Theorem provides and extremely analytical listening experience, with the crispness you expect from solid state. The soundstage it provides is extremely wide and enveloping. All in all I was very happy with the Theorem and wish I could have kept it.
Cons: What killed it for me was that I primarily will be using this with my JH16's and the second you turn the device on even in low impedance you hear a extremely audible constant hiss. The noise floor is extremely high, I have had a small pico amp/dac and I never hear a hiss. This becomes incredibly distracting when you are trying to listen to recordings that have quiet passages as the static hiss overwhelms the music. I emailed David from Cypher Labs and he told me to just return the device for a refund, so I guess it isn't a defective unit. This device is really exceptional except for the high noise floor, if you are using these for non-IEM applications it should provide great performance in a small package.