The TDA2822 is obsolete and was cheap. The schematic from Sony show that each channel has two capacitors not shown on the datasheet that might cause the TDA2822 to oscillate creating hiss. The datasheet shows that the distortion is high.

 

It is not a "normal op amp". If you look at the datasheet, the triangle simply represents one "amplifier module" and the gain is preset internally with input resistor and feedback resistor are inside the two amplifiers in the package.

OK, and I should have realized that with the "TDA" type number. I do recall the comment of one audiophile co-worker about SSSSSony audio appliances. He asserted that they all suffered hiss. I do recall that was a problem with one cassette deck that had it's equalization used to extend the frequency response to well above 10KHZ. There is a limit to what equalization can do correctly. Hence the development of the Dolby system. Sounds good, but not "true High Fidelity." Funny how that works some times, isn't it?

 

Have you checked for snakes?

 

Have you checked for snakes?

No Snakes!!!
Some transistors are just noisy, high frequency hiss. That is a penalty of getting high gain with cheap transistors.

 

The schematic shows the M version of the 2822. It is more like a dual LM386 than any kind of normal opamp. I used it to drive the active termination networks on VME and VXI backplanes in the 80's and 90's, and it was noisy back then, but not enough to matter in that application.. I never knew if it was the input stage or the voltage amplifier, but I was leaning toward the voltage amp because a portion of 6 mA should be more than enough to quiet down the input stage. The NE5532 is older and has the same typical operating current, and yet is super quiet.

ak

 

No Snakes!!!
Some transistors are just noisy, high frequency hiss. That is a penalty of getting high gain with cheap transistors.

I sm just very safety oriented. Can't be too careful.

 

I sm just very safety oriented. Can't be too careful.

I have seen far too many examples of "to careful!" It happens all of the time. and the results can be very ugly.

 

Try an in-line passive volume control for headphones, or build a fixed attenuator.
https://diyaudioheaven.wordpress.com/headphones/headphone-attenuation-adapter/