Op Amp blind test: Burson, ADA4627, NE5534

To quote @Markw4 here , we will be using our ears to measure each op amp for richness and overall thick goodness, quantifying this with the scientific unit µRiches (~100µR being a common value for opa's as we all know)

It is said that the moderators take a dim view of forged quotes. At least the link you provided shows what I actually said. Please try to be more careful next time.
markw4, feels like you're looking for a specific answer. If you make a suggestion or point me toward a resource so that I can learn, I would be happy to absorb that.

Here are some for starters:

I guess the first thing you might want to decide is whether you want to use preference testing, discrimination testing, or some combination of the two. I would suggest the latter.

Mw4, apologies if my post sounded adversarial. Intended as just a bit of silliness. I agree with the point you made in that thread.

Again, as I said in post #1 I have some opinions on op amp swaps in general. Certainly we have all read meatheads on headphone forums where users compare op amps

I think it was cool that Mr Burson sent me some parts, and many people including nelson have played around with discrete opa. We are just having some fun
Okay, cool.

Here's the thing I would ask you to consider: It is virtually certain that some of the newer IC op amps will out-perform any discrete op amp in terms of measured distortion, noise, etc., the things AP machines measure so well. So if some people prefer the sound of discrete op amps, why? It is so simple that they like a little distortion added to their reproduced sound? Or, is it more complicated than that? Is there some way in which discrete op amps can more accurately reproduce music better than IC versions do? If so, what exactly is the perceptual improvement?

Of course, in part what sounds right will depend on the rest of the reproduction system and the recordings chosen for comparison. IME it is best to choose a small number of reference recordings and learn them intimately so that any small differences are immediately recognizable. One good example is Janis Ian's, "Breaking Silence." From that one recording an expert listener can tell a great deal about a system. Too many recordings and or poorly made recordings may tend to make accurate test results more difficult. Again, this is just IMHO and IME.
I hear you loud and clear! In post #1 I draw attention to the high THD measurements in the Burson op amps, mention the Pass H2 and SIT products, and theorize that harmonic distortion might affect the way we perceive spacial cues (although this is more of an idea than I hill I would die on). Again, I'd like to emphasize that this is not my area of specialty and that I do not do this occupationally.

I don't want to put words in your mouth, but I think we may be on the same page, or close to it.

I will check out the Janice Ian song you mentioned.

Here is a playlist I have put together for our event which features some music I feel I am familiar with enough to pick out differences in presentation: https://music.amazon.com/user-playl...c65a5sune?ref=dm_sh_2cd1-93a8-34a1-f591-8f2a9

Very likely we will not use every track. But there they are.
Hopefully you are not going to stream tracks from Amazon music? It would be lossy compressed. The other problem that should be addressed is to make sure if using some kind of computer to play music that the OS isn't messing with the data. IMHO bit-perfect CD playback should be a minimal requirement.
I will follow for honest eval, but just have to tell a funny story. Someone with a Parasound ZAmp changed the TLO74 for one of these and went on to rave how it changed the world and made the ZAmp so wonderful.

Well, that chip is the SERVO chip and I am surprised it did not oscillate to beat all get out as the very high impedance of the circuit requires the FET input. Changing the op amp does not fix the bad AC shielding or terrible distortion caused by the current sense and shutdown circuit. DC servo. Could it help? Maybe if everything else was fixed first.

Of course the 5534, as revolutionary it was as the first legit HI-FI op amp, is a 10 cent dinosaur not not in the league with the newer chips. By a couple orders of magnitude. If the rest of the circuit is good enough, I would HOPE you can hear an improvement. FWIW, a lot of studio boards are full of the Signetics. So for those uber-high end purity folks, sorry, the jokes on you.
Well Mark... then it will be worthless :p

I will be scoping the circuit with different op amps as well as measuring DC offset before we listen to them to check for stability / clipping / oscillation / etc etc as per the Mooly thread I linked above

I am not a senior DIY member, I am here to learn, listen, and have fun. This project is about me learning how to read spec sheets, learning how op amps behave, and having friends over for a good bowl of pasta (gnocchi preferably). I am introducing a level of blindness into the test for fun, but to your point even then anyone reading this thread should not take that as rock solid empirical collection. It is what it is - couple of folks getting together and tinkering
Well said Anthoney