Finally, another update:
Today I decided to just deal with the super-hot spare room in which I do my DIY audio work, and install one of those new 8 DIP gold-plated sockets pictured above. To refresh your memory, I originally removed the stock op-amp from this headphone amp, installed a run-of-the-mill op-amp socket, then an LT 1365 op-amp, and was very pleased with the sonic improvements.
Not long thereafter another AK member suggested that the type of socket I'd installed was generally inferior to the other type, which has gold-plated circular sockets for the op-amp pins. According to him, it's a question of long-term reliability and therefore performance. According to me, it's always nice to have gold plating for increased durability.
So I opened 'er up this afternoon and within mere minutes had removed the old socket, and installed the new one. Piece of cake, seriously. I had more trouble getting the LT 1365 op-amp out of the socket before removing than I did installing the new socket. Here it is:
Since that took me all of four minutes to complete, I decided to take it a step further and remove the stock left and right positive wires from the only pair of input sockets I use. I replaced them, as you can see below, with some solid core 22awg copper I had lying around (I have a lot of wire just waiting to be used in such ways, and "a lot" is a huge understatement actually
). In the past I've always preferred solid wire to stranded, and the latter is what the stock wire was. Moreover, changing the wire to solid copper 22awg is closer to what many of my own interconnect designs use, therefore theoretically making it closer to an extension of the interconnects attached to the RCA sockets on the back of the amp.
Will it help? I don't know, but it cost me nothing but time to do, although I must say whoever originally assembled this thing used too much solder at the RCA positive pin, which made it a pain to de-solder. The stock left and right channels for all the inputs are black and red, and in the pictures you'll note that I used clear and purple (the insulation looks blue in the picture, but it's actually a light purple):
Finally, I installed an Analog Devices 826 op-amp in the new socket and off I went. Too early to say for sure what the effect of all this may be, but the sound did seem distinctly smoother and airier when I tried out some familiar reference recordings. In all likelihood, that's due to the new op-amp I put in there.
In any case, this amp is great. I'm not finished with it either, stay tuned...