The LM4562NA sounded terribly lean and thin. I couldn't listen to it. I put an OPA2132PA in instead and listening to that now. I also have OPA2228P and OPA2134PA that I expect will work.
You are fooling yourself again. They are both nearly identical in performance in most applications. In a few, the LM4562 will excel, but not in a typical audio amplifier.
Here is an Elliott Sound Products preamplifier,
Project 88. It has a pair of gain stages, non-inverting for the record, the details can be found at the website if interested. It's a good kit preamp, I have built a few projects around it.
I built up a borad with sockets so I can swap. More on sockets later.
I have some NE5532, OPA2132, and LM4562 opamps among my stash.
Here is the OPA2132:
That's great distortion and noise performance.
Here the performance with a pair of NE5532 replacing the OPA2132 devices:
Slightly better noise and distortion than the OPA2132, but the OPA2132 has coloration so far below human perception, you have a better chance of hearing a pin drop a mile away.
Here is the performance with a pair of LM4562:
While it has the best Signal to Noise, I think I may need to address the surrounding circuitry in order to get the best performance, you can see some low level hash at -140dB. You can also see some spikes at 17kHz and 19kHz on the LM4562, they also appear to a lesser extent on the NE5532 and even less on the OPA2132. Those are the LED lights in my shop, and the Opamps are each amplifying harmonics to a greater or lesser extent.
Not that any of this matters, I can't hear this, and sorry to say neither can you.
Your situation is different than mine. If your gear is crap, you might get some woeful self-oscillations with high-bandwidth Opamps. NE5532 is one of the safest bets. But I don't think your gear is crap.
If you have been swapping Opamps, you will wear out the socket. If you have been hard on the socket, it is possible you have already worn it to flakiness. Trying to get devices to play with less than a part per million of noise and distortion does require that the amplification stages are really well electrically connected. The reality is, if you really wanted performance, you would look for a manufacturer who avoids the problems and noise introduced by wedging pins into sockets. I would be concerned that at some point you will actually degrade the contacts to the point where the device doesn't work properly. DIYAudio is littered with gear wasted by Opamp swapping. Probably ASR too.
In reality, probably nothing going on, at least I hope so, otherwise you messed up the socket or (better) the pins on some of your Opamps. Swapping Opamps provides no benefit, but does provide an avenue for our imaginations to run wild, and for us to fool ourselves into thinking we heard something, all while wearing out the connections inside of your gear.
edit: fixed mistyped Opamp name
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