Thd 1khz simulated: ~0.040%
Frequency range -1dB: 1hz - ~60khz
Slew rate: ~50V/us

zAh 2

Thd 1khz simulated: ~0.005%
Frequency range -1dB: 1hz - ~60khz
Slew rate: ~30V/us

zAh Ng

Thd 1khz simulated: ~0.002%
Frequency range -1dB: 1hz - ~60khz
Slew rate: ~50V/us

Link to schematic of zAh1 (single ended and as linear as possible, even more than zah2
Link to schematic of zAh2 (Built to be as linear as possible in the core, without going mad)
Link to schematic of zAh-ng (NOT built to be linear but has a circuit to negate the errors VERY effectivly)
Link to schematic of zAh-HYB (This is NOT the average srpp hybrid although it looks like it)
It started 2002 or something like that with a simple voltage follower current amplification stage with a P and N fet.
Altohugh the cd player made a pleasent listening volume I wanted a little more volume. I ordered 4 vacuum tubes (6N1P) and found a preamplification circuit called mu-follower. Power source was at that time a big heavy toroid transformer. I used that amplifier a few years.
In year 2005 I took up development of the amplifier. The transformer was replaced by dc/dc swichmode converters by vicor and tube preamp was replaced by a simple transistor preamp circuit. By the end of 2005 the amplification circuit was developed further and at present there will be no more development for a while. the circuit uses 5 irf9610 , 2 irf610 and 2 bd139.  A little odd choice one may think but it works surprisingly well. My intentions was to use as few components as possible but I found  some components are really needed to make it work good.. The thought was also that one shouldnt have to match transistors to achieve good performance.  In the middle of october 2006 I finished the basic design of a complemenatary version of the amp, simulated data is very promising..  At home i still use ZAh ONE as my basic amplifier though..(2007:) Since  I have felt more and more confident in the construction over the years now I've sort of split myself into two paths, the "i dont mind a little thd"  path  and the "There should never be any thd" path.It makes the focus of constructions a little easier. I now manage to not have any output coils to protect from  capacitive load. And also thd anylyzes shows mostly tube-style third now if present..