I have just finished changing out the NE5532 op-amps in my JVC XL-Z1050TN CD player. So your post is kind of relevant. I replaced the through the hole NE5532's with surface mount AD825s mounted on an adaptor mini-PCB made by LC-Audio. But I know that brown dog make similar adaptors also.
I don't have vast experience changing out op-amps, and have gotten into trouble in the past. (I'm still on a learning curve.)
(I made a major boo-boo once when I replaced the NE5534 op-amps in my A&R Cambridge A60 amp's phono stage with some AD826 types. When connected my LP12 to the amp, all I heard was the deafening sound of silence. Basically I had replaced a op-amp which works on a voltage feedback principle (the NE5534), with a high speed video op-amp (AD826) which works on a current feedback principle. So I warn you, there is more to this game than just checking that the from/to op-amps have a compatible pin out!!!! Suffice to say 2 new NE5534 chips went back into my A60, and music was restored. Boy did I feel dumb afterwards!)
Based on the above stuff up, changing the op-amps is the first mod I have made to my JVC CDP. I wanted to be sure that the machine still works!!
Also I had it on good authority (from LC-Audio, and another local aussie company), that the AD825 is a common swap out for the NE5532 chip.
Now in terms of the sonic benefits....
Basically the improvements were well worth the $80 aussie dollars I paid for my 4 AD825 modules. The JVC uses 2 op-amps in the analogue filter, and 2 op-amps in the output stage. I replace all four NE5532s with the AD825 modules.
In terms of listening, I got the following significant, but not earth shattering improvements:
1) better articulated bass, the bass was ever so slightly mushy with the NE5532, and was a bit firmer/tighter with the AD825 2) smoother mid-band, the NE5532 was a bit harsh, the AD825 is smoother in the mid. This is the best bit for me. 3) also when the music is really loud, there is slightly less congestion to the sound, this is not major, but a small worthwhile step forward.
I have lots of other mods planned for the JVC, but at the moment I am time-poor, due to work commitments. I plan to upgrade the clock in the JVC, with a Burson Audio "super-clock". Also I plan to upgrade all the passive parts on the audio board when I finally get some free time.
So in summary, op-amp changes for me are not earth shattering, but worthwhile since the cost of the mod is low. I think this is quite a well trodden path, but there are a lot of pitfalls for the unwary. I have been lurking around a lot on the diyaudio.com web-site reading posts from people more experienced than me.
Also as an aside most people, recommend the #1 CDP mod as being upgrading the clock. I also own a XA-5ES that I had modded for me, since it involved a lot of mechanical work. The clock in the Sony XA-5ES is improved, and I can safely say that upgrading the clock makes massive and fundamental improvements to the sound of the machine. The only gotcha on clock upgrades is that the commercially available "super-clock" modules are pricey, so you need to ensure you don't over capitalise on a humble machine.
hope this helps some, you really need to do your DD on op-amp swaps since some op-amp types are very cranky, and need a specific circuit config, such that they cannot be swapped out for other types which appear 'pin-compatible'. But as I said there are knowledgeable resources out there, like on diyaudio.com, where you occaisionally find major designers like Nelson Pass, and Guido Tent hangin' out.
one further point, another small practical matter. When I was working on my A60 amp, back when I made that fateful op-amp change...
Before starting work, I did figure that I would install some IC-sockets, just in case the AD826 was not going to work, so I could easily swap back in a fresh pair of NE5534's (or other compatible op-amps). So I went ahead and ordered the best sockets I could find on the web, these were of a copper and berrylium material and had tulip shaped receptacles. But having very cleanly desoldered the old chips, I found the new super-duper Cu-Be sockets would not fit in the PCB holes, the legs were too fat.
Now I could have bored the holes out, with a slightly larger drill bit, but at this point I was too chicken to do so in case the the drilling lifted the copper pad used for soldering the pins.
So if you plan to fit sockets so that you can later swap out op-amps willy-nilly and try the latest and greatest types, you may want to check out a few different types. Or, be prepared to bore out the holes, ever so slightly.
A friend of mine is working in NAD and he said that the "most compatible" swap is the OPA2134 which is the opamp they use in the higher version (C542). I asked him if the OPA627 with brown dog adapter will be compatible, he said that they don't use this opamp for some reason (not ROHS compliance). In DIYaudio.com, somebody mentioned that opa2134 is not a worth of a change cuz you can't tell any difference at all. It's just waste of time and money. If I go to opa627 mods, it will cost me around $110 US and if it doesn't work, for me that's alot of money to waste.
if your friend is working for NAD, I don't think I will be able to offer any better advice.
But it is in fact a reality, that when you start modding your equipment, risk is inherent. It comes with the territory!!
I cannot comment specifically on your machine, I am not experienced enough to do so. You need to find people who have already modded the same machine.
I know with my JVC, going from NE5532 to AD825, the improvement justified the cost I would say.
Also you need to be careful, there is a lot of hype in the DIY community also. I have seen commercial modders make statements, like changing op-amps can make massive improvements. This in my opinion is not true!!
If I were to make a single mod to a CD player, I would upgrade the clock and stop there.
The steps you need to take are the following: 1) find out from someone who has already done the work, which op-amps will work as a straight swap out. 2) bite the bullet and just do it. You may be pleasantly surprised or you may not. Either way you will learn something...
Thanks for your straight forward warning/comment. My friend didn't make any comment on their product as well cuz he's not sure about any opamp especially the higher grade.
Just a few points, I only mod my equipment when it is 1) old and 2) I tend to have another replacement already.
E.g. my JVC player is 15 years old, and I have a Sony XA-5ES as my primary player that I had professionally modded for me.
I modded a A60 amp that I bought in 1987, but I also have a brand new AVi Lab series integrated amp which is my main amp.
But both the A60 and JVC, are decent good quality pieces, that have a lot of potential for improvement by selective mods. This is my strategy. I guess I am doing this as much to learn, as I dont really need the sonic benefits, this stuff is for my 2nd/bedroom system mainly. With this strategy if something goes wrong it is not the end of the world.
I guess what I am doing is kind of weird, but it is really for my own interest and education. Persuing this path is kind of helping me appreciate what are the real values of good equipment, as opposed to hype put out by unscrupulous manufacturers and magazines.
Also I don't tend to worry about the cost of the mod too much for the time being, since I am more focused on what I am learning.
I am not yet sufficiently experienced/confident to buy a brand new expensive unit, and then go straight into extensive mods.
If your end goal is really to improve your system sonically, another strategy would be to sell the BEE, and buy a better player. And if the goal is the best sound possible, I would definitely look at the 2nd hand market. Amps and CD players tend to last okay, so long as they have not been abused. You get much more bang per buck buying second hand, for me it is the only way to go, unless buying something very fragile like a phono cartridge.