I'm about to embark on a thorough restoration and re-working of a very clean AU-999 on behalf of a fellow SNAer.
All of the parts have been acquired, including Nichicon Super Through top-of-the-range filter caps, Elna Silmic IIs for the preamps and signal path locations, Nichicon HEs for the power supply, Nichicon ES for the bipolar caps, some Panasonic ECQV film caps to replace the 1uf electrolytics and below, and some AXON polypropylenes for bypass duties. The troublesome 'flying saucer' transistors will also be replaced with new equivalents.
In addition, a bunch of new metal film resistors will find their way into a few critical locations. A few techs on Audiokarma have identified deficiencies in the original preamp circuitry, bass EQ circuit and subsonic filter circuit, and minor mods to these circuits make a tangible improvement in clarity and bass extension, whilst also ensuring that gain levels throughout the amp are better matched.
Apologies for the initial crappy photo, as my main camera was misplaced during our recent move.
I'll provide ongoing pics of the restoration process, including some pics highlighting the build quality of these older amps. There are several nice touches like prope resistor ladder stepped attenuator controls for the bass, mid and treble, as opposed to standard potentiometers.