Full Review with pictures and unabridged text: Graham Slee Voyager headphone amp in review - plastic surgery done right
One of the best bits is that its smooth, warm nature. There is no grain and no harshness anywhere. BUT, thankfully, it has an underlying layer of fun and power.
It is particularly well-suited to headphones such as the DT880, a host of Ultrasones, and surprise surprise, the Final Audio 1601 series. The reason is because of its warmth, but also because it packs a lot of power within its usable volume range.
One thing I appreciate about the DT880 is how well it scales up the wall. The spot near the ceiling is still an out-of-production Meier amp which I used to own (and forgot the name...), but a couple of spots down (and in terrific in its own right) is the Voyager.
There is no portable (not talking FiQuest or Lisa here) I have used which brings out such lovely textured bass from the DT880. It isn't desktop amp powerful, but it is deep and grainy. The Ultrasone DJ1Pro, however is where the Voyager shows its colours.
It goes 90% of the way in terms of dry, deep bass response with the Voyager while keeping pace up top. I have used more powerful, expensive portable amps, but for this 64Ω headphone, the Voyager outclasses all of them.
Build quality is, apart from looking like a pillbox, amazing. All of the in and out ports are easy to get at and Jalco ports are amazing to be sure. Secure, snug and fit, they grip the headphone or line in very well. Taking the amp apart to change op-amps is also simple: just untwist four bolts, flip the switches to 'battery' and then 'contour', and voila!, the case slides easily off.
The large case affords a neatly laid out circuit which is oh so easy to get to. Despite being plastic, I have not suffered a single instance of interference, but I will admit to not using the amp that much whilst on the bus as most of my portable earphones are balanced armatures.
At its price of ~255$ US, the Graham Slee Voyager more than makes a dent in the portable amp market and kicks way higher than its cost of ownership.