IMO this by far the most advanced headphone amp in terms of design and materials used. It's by no means an easy task to build a Blue Hawaii in the first place due to the voltages at hand and the massive amount of heat the amp gives off. This is a 200W+ space heater and Justin has gone to great lengths to make sure that it will last a long time by providing efficient ways to get rid of the heat. The tall cones are vital part of this since they allow cold air to reach the underside of the chassis to cool the tubes and the surrounding circuitry.
As for the choice of parts, many of these amps have the best volume attenuator money can buy, a 4-gang Alps RK50. The amp is fully DC coupled so no caps in the signal path to degrade the signal and the PSU caps are made by CDE and Panasonic, both excellent choices. RCA sockets are PCB mount Vampire units and the list goes on and on.
Pretty parts are just band-aids on a bullet wound if the circuit design isn't up to much. The Blue Hawaii and the Stax SRM-T2 stand IMHO head and shoulders above all else when it comes to circuit design and Justin has gone quite a bit further then Stax ever did with the T2. Such small design details as to make sure there is zero interference on the bias line and that there is no bias charge hiding inside the amp section when disconnected from the PSU shows just how far Justin has gone here.
For the record I have one of these on order even though I'm more then capable of building one for myself. The reason is simple, I owned one of the old KGBH units that Justin built and it worked flawlessly for years of heavy use and was beautifully made.
