Hi John,
Hugh, being rightfully cautious regarding his intellectual property--so he can eat, feed his family, etc.--provides detailed instructions, schematics, and all that only to people who purchase his kits and upgrades.
I've done the Nirvana upgrade to all three of my AKSA 55's, but it's been a couple of years at least. My seat-of-the pants estimate is that the Nirvana upgrade replaces maybe 20-30% of the original parts with upgraded parts. It took me several evenings to complete each one, but I work slowly.
The N+ upgrade replaces only a few key parts (and slightly modifies the circuit)... this could be completed in an evening or two, even at my slow soldering rate. The N+ mods are as easy as it gets in DIY.
In both cases (N and N+) you need to re-bias the amp... the changes are small, but you will want to be sure.
The sonic impact of the Nirvana upgrade is anything but subtle. You will hear more clarity and transparency in the highs, more definition and impact in the bass.
In my system and to my ears, the N+ upgrade was absolutely transformative. I have been a tweaker for almost 5 years now and I have never heard anything close to the impact of the N+. The highs are so extended and clear, and the bass... I could easily hear (and almost feel) the difference in the bass from my bedroom, one floor above my listening room. One very respected audiophile recently wrote that the 55N+ could be best amp he has ever heard. Every CD in my collection now sounds different, and way better.
IMO, if you build a stock AKSA and listen for a while, you know (like YOU do) that the AKSA is very much for real. You can be assured that the N and N+ extend the muscle and finesse that Hugh designs into his amps and IMO are very much worth the relatively modest time and expense it takes to get there.
Good luck,
Peter
