I've had this in my system for a few months now, and I like it. It looks great sitting right on top of my Corda Headamp!
Anyway, besides the nice fit, finish, and appearance, it is an intriguing product. It does 2 things: 1) give you an adjustable bass boost, 2) filter some harshness from the highs. This thing does not hit you over the head with its effects right away. It is quite subtle, but I do believe it allows me to listen for longer with less fatigue than previously. It also reduces the possibility of headaches that you might get, just from being overwhelmed by detail and brightness of the music.
Right away I threw in a Miles Davis CD I was listening to, then started playing with the filter control. All that trumpet (or saxophone) can start to wear you down after a while. This type of music I might just play over my stereo and not use headphones at all. But the Analoguer did a lot to make a headphone experience a lot more feasible. In the case of Miles, I left the filter on the highest setting, and it made a big difference.
My favorite headphones are Beyer dt931. Some people might find these too bright, and so these may be a good match for the Analoguer. I don't think everyone needs this product.
However, I should make sure to say that this is a sonically very high quality product. It would be very easy for a filter to just ****** up the sound, of course! But the Analoguer does not, and is virtually transparent. It adds no haze, glare, or any other deleterious sonic side effects that I can detect. I've sort of taken this for granted so far in my review, but it's not always easy to find a filter that a) does no harm, and b) has actual benefits.
So, for people that think they might have a need for a filter product like this, I'd say check this one out, it is a well implemented device. If Jan still has his promo on, it is a great opportunity to try it out.