Yes, I will collect something. This might need a bit of time, as this all is a few years old and I have to search for documents.
However, two of the best sounding amplifiers for my ears, that I have build so far, can be found on the net:
1) More or less the same structure as described above, using a two stage OPAMP approach, but replacing the second stage with the brilliant LME49600 amplifier from National (now TI). For the first stage I used an LME49710, which is even better in terms of noise and THD than the formerly mentioned OPAMPs. Of course it always turns out to be a question of personal belief, whether you really can hear the difference between different first stage OPAMPs, but in the end I was quite happy with the sound, and maybe this is because the guys at National simply did a good job in matching the characteristics of these two devices.
I found a schematic on the net, which more or less shows the circuit I used: http://www.twistedpearaudio.com/docs/linestages/ventus_ez_schematic.pdf
. You only have to add the volume control in front of the input stage.
2) The QRV07 design done by Per-Anders Sjöström using the TI TPA6120 as an output stage. This is a really good amplifier IC with outstanding datasheet values and a heavily convincing sound. You can find the description at http://sjostromaudio.com/pages/hifi-projects/36-hifi-projects/93-qrv07-headphone-amp?start=2
. I bought one of the PCBs from Per-Anders, because they are not that expensive, and the TI chip is definitely not suited for a breadboard approach. First of all it's SMD package only, and second it needs a good PCB layout to function correctly. As a pre-amplifier I chose AD8610, but I did not much experiments for this particular first stage OPAMP.
The simulation software I used for the headphone amplifiers on board level is PSpice. I wrote some small scripts to convert the netlist generated by Eagle into a suitable format, but this definitely did a better job for me, than directly using Orcad for schematic entry.
Lately at work I had to build some boards using Altium, but until now did not try to use their simulator. It is always a bit of work to get the models delivered by the IC vendor (if they exist) into the correct format for the simulator. This worked quite fluid with PSpice.
For more elaborate circuits combining Digital and Analog I tried some AMS software as well, especially Mentors ModelSim/Eldo and Cadence's NCSim/Spectre. But these are Linux based tools without a graphical user interface, and therefore I cannot recommend using them without the intention of really digging deeply into the usage of these tools.