headphones amplifier on TL072 &2*TL084

Most important assumptions for that project was to eliminate sound noises, and noises from cell phone. I had un useful ( because of low quality) PC speakers, and I decided to rebuilt them. I choose TL072 it was good choice for preamplifier. Amplifier played well but I wanted more power , that’s why I put 2xTL084 from broken cd rom. I used aplicationds diagram from datasheet. .
Speakers that I mentioned, were 1,4W system ( for 3W speakers). I found transformer with 9V 0,2A. It was plug to power slot. Power button was at one of phase of secondary winding. That was first element that I have tuned. To get symmetrical power I need to split Uz2 for 2. So I need to make output in the middle of winding. I used thermo- conduct paste at the top of winding and boards for better cooling.
It works. I don’t know why I got sin2V more, but it is even better. Voltage difference at symmetric branches after rectify is max 50mV and I got about 2*8V. Even with full power it don’t heat too much.
I made some tests. Firstly I tried to put some filters because my headphones plays stronger basses, but finally I removed all condensers. I wanted to use amplifier with PC, that’s why I didn’t put any noise filters.
To keep all elements together, I made board with the same dimensions, with a few elements in the same place. From very beginning I wanted to put integrated circuit as far as it possible from current source. It wasn’t very easy I must say.
I put two diodes on two half of power source. Power cables are solder to power button. All elements for 230V are secured by silicone glue to avoid electric arc.
Second gain level: I made another board for it. In the middle of it I placed 2*TL084.
Here you can find diagram https://obrazki.elektroda.pl/16_1264294115.gif
Here is original text: https://www.elektroda.pl/rtvforum/topic1550332.html

I didn't exactly understand, if you used a parallel circuit of 4 or 8 single OP stages?

According to the datasheet, a TL084 has 192 ohm output resistance, not considering the output transistors, so the output
voltage of a x4 parallel circuit is considerably reduced, you'll hardly get more than 100 mW into 32 ohm load, possibly even less.

As an additional issue, the TL084 input offset, in combination with the factor 10 gain of the amplifier could create big problems
with the 1 ohm output series resistors. They should be increased at least by a factor of 10.

I think, a two transistor complementary class AB output stage with a single TL084 driver and overall feedback would give a better
headphone amplifier.