Arcam CD72 Output Stage

[senshu]

Dear diyAudio members,

I originally posted this message to hifichoice.co.uk (Arcam's country), and guy there suggested me my issue is sitable for diyaudio than hifichoice.

Now, I am modifying Arcam CD72 CD player, and would like to have some adivices from you. I am an almost pure software engineeer and is lacking a sense of electoric issue.

I did changed and added some of electrolytics, added power transformer for op-amp supply, and now I am facing how I can improve output stage including analog LPF.

Below URL is my CD72 modification history, still on going. Though all the texts are in Japanese, but you can see figures including circuit diagram.
http://www.cameraguild.jp/123/hifi/cd72/index.html
I have a plan of translating this site nto English, but not so soon.

I checked Arcam's PCB and got their LPF/output circuit design as described in the 3rd picture in the below page.
http://www.cameraguild.jp/123/hifi/c...805/index.html

I have four questions.
Q1) Does anyone know if this my circuit description is correct?
Q2) Due to avoid the interference of non-audible carrier frequencies from many sources at the mixing console, most of manufacturers, including Arcam, adopt very physically high performance LPF. But for most of listeners, just plug CDP to amplifier/speaker, I believe, such a physically good LPF is not required, or even is bad from signal purity perspective. Is this my understanding correct?
Q3) If my above understanding is correct or passable, what options are possible for modifying Arcam's LPF/outpit stage? Simply eliminating 1st OP-amp and use only CR filter can be one option, I think. Is anyone has any other good idea?
Q4) OP-amp. Original CD72 uses two NJM2114D dual channel amps. I already changed these to AD827JN and I personally love this over 2114. I am planning to use OPA627 for next step. Anyone has any better recommendation?

Your any comment or suggestion will be highly appreciated.