I have just completed a 100 hours burn-in of the iQube. As it is not using super-huge caps I believe it has quite settled down by now. I have been using low-gain setting, and feeding the iQube from a iPod Nano playing Apple lossless files - mostly classical, jazz and some smooth pops. I did not use the mini-mini cable that comes with the amp. Instead, I was burning-in the iQube using one of the first Qables GoldCap mini-mini that Hans made for me.
The set of AAA batteries that comes with the iQube gave me 90 hours of continuous play time (using a Grado RS-1) before the LED starts to blink. For those who are traveling this should be more than enough for any long haul flights.
The iQube is one of the most professionally made, packaged, and presented headphone amps I have ever seen in the market, especially at its price. Looking at the iQube, one may find a light shadow of LaRocco Pocket Reference II, but having owned both, I would say the iQube is more advanced in casing design and choice of material. The PRII is definitely a piece of machining art, but the iQube displays a level of attention to details that very few amps, if any, can surpass. It is also a bit lower profile yet constantly elegant - a design that I am sure will withstand the test of time.
I am not an electronic guru so I am not qualify to tell the difference between a Class D headphone amp and other designs.
Soundwise, the iQube is totally different from the Pocket Reference II. The Pocket Reference II sounds coloured by comparison - although I have to admit it is a beautiful colour. The iQube does not exaggerate. It is not an agressive, all in you face type of amp. It is slightly laid back, highly resolving, but most importantly, maintain a very good balance and proportion across the whole spectrum of audio frequencies. May be I should say it is neutral (and this is extremely difficult to achieve for a battery powered portable amp). I can listen to it for hours and never feel stressed or fatigue, regardless of the genre I am listening to. The iQube is pretty truthful to the source - if the source gives you deep bass, you hear that. If the source contains sparkling highs, you hear that too.
For those who are looking for "wow" factor in sounds, the iQube may not be your first choice. It is elegant, honest and always wanted to stay out of the way. For quite a few times, listening to the iQube for some hours I feel that the amp is no longer there. It is a true "hi-fi" component.
Downsides ? Yes. The battery compartment is, as I said in the other forum, a brain challenge to open. The beautifully prepared printed manual helps, but it will still take a few attempts before I succeeded. But after a few times the process becomes much easier. On the other hand, I started to feel some very slight rattling on the casing (the batter compartment cover) after a few "open and close" excerise but this is not a big deal - everything is still intact.
All cable entries are on the rear of the amp. Some may like it, especially when you put it on a desktop, but when traveling there is always a worry that cables may be compressed when the amp is in a vertical position with the volume knob facing up. At least I won't try this with my GoldCap
Also, the iQube accommodates 3.5 mm cables only. For an amp with this quality, a RCA input pair will make it a very good candidate for desktop application, especially in office environment.
But overall, I am very impressed. The iQube has set new standards in many dimensions in this nitch market - product packaging, design, workmanship, customer service, and it is a class of its own when it comes to sound.
F. Lo