- noise level and being audible: yes, in headphones and good speakers, you can hear these things. as each stage improves (the dac, the pre and the final amp) you do hear more of the recording (which most people do consider a good thing). and yes, 130db down is still audible in headphones on classical music that has good dynamic range. its not flat 130db either, that's a best-case null point. on average, things that are 'good' these days tend to be 100db or better but that's a real honest 100db, not some marketing specs.
You say -130 down is audible, I say it's not under any conditions. Only an independent double blind testing protocol could determine which of us is correct. Your opinion, or any one's opinion, even mine, is not fact and should not be stated as such. Your making the claims, so the burden is on you to prove those claims if you wish. Otherwise you have posted your opinions well, but they remain just opinions. Measurement is not listening, and opinions are not provable repeatable facts.
- upper frequence response matters. you need a few times the audio passband worth of FR to pass the audio band cleanly. modern pre's tend to want to have good response up to 50khz, 100khz and beyond just so that the '20-20k' gets thru easier. send a square wave thru at even 10k and watch it as it goes thru a high bandwidth amp vs one that is 'just enough' to pass 20k. the fidelity of that wave is visible on any scope.
That sir is rubbish. You can see extended FR with a scope, but you can't hear a difference past the upper FR of human hearing. Content above a given hearable upper limit does not modify the content below that limit. Plus, what audio media do consumers use that have content past normal human hearing frequency response. Most don't listen to frequency generators!
- 0.5db steps, it matters to get you a smooth transition as you vary the knob. I tried single db steps (for almost a year, on one of my protos) and thought 1db was pretty ok for daily use. then I built a half db stepper and liked it a lot more. costed 1 more relay and a few more resistors. was worth it. and for a subwoofer box, I built one that uses 8 relays and only gives 25.5db for total range but it moves in 0.1db steps. yes, for a subwoofer level control, you do want that level of granularity. try getting that from your sony
Again I'm sceptical, but as stated before only double blind testing is capable of separating fact from opinion. My current Sony component setup is just one of a large number of systems that have passed through my hands. I'm not even sure it has the best specifications of the stuff I've owned, just the system I enjoyed using the most.
- re, high end spkrs; yes, I have looked at the FR graphs. some of the modern tweeters are truly amazing. you can buy tweeters for $50 or less that are flat out to 30k. modern tech is WAY beyond what we had even 10 yrs ago (its a good thing, btw). along the same lines, if you use good headphones (my ref pair is sennnheiser hd580 and hd650) you will hear every little detail and it will be quite flat sounding. cheap speakers and phones are limiting but modern systems are not.
I too enjoy owning a pair of Sennheiser HD580 cans. And of course a tweeter does not a complete loudspeaker make, it's just one of many parts that comprise a modern loudspeaker, including crossover, other drivers, cab design, etc. I'm sure some speakers have improved over time, but I'm also still sure that speakers,normal human hearing and listening room properties, are still the ultimate limits or FR and distortion and further improvements in up stream electronic components is just gilding the Lilly.
- servo speakers; not necessary. even conventional cone (boring) spkrs are very high fidelity these days. I think you're just quite out of touch and not willing to update your world view, sorry to say. a LOT has changed since the days the dinosaurs walked the earth. old classic gear can be treasured for its 'sound signature' but performance wise, its usually not competitive. there are a lot of exceptions but I would not consider a mass market sony box of any kind - no matter what the company claims - to be competitive with custom made DIY audiophile gear. for lots of reasons.
I'm still a member of a popular audio forum and I think I have tried to keep up with audio evolution. However I'm still of the opinion that the vast majority of audiophile 'golden ear' equipment is designed only to separate dollars from their gullible customers. That is OK, if they can afford it, it is their privilege to waste their discretionary money anyway they wish, just don't tell me all the claims are fact. I love those Lexus TV commercial showing a audiophile staring at his tube audio amplifier and saying "there is real gas in those tubes". 
Lefty