Cmoy distorts until i put finger below opamp

[polumenta]

Hi
I made CMOY on stripboard with (lovely ) NE5532AN. When i listen strange things happens. My amp distorts on line level. It sounds ok only on very very low volume levels.. I get same results if i turn down volume on the output of the soundcard or pot on cmoy.

BUT, if i put finger below opamp touchnig all 8 pins (or another one place on stripboard I found), than cmoy sounds normal, without distortion. It gets even louder for aprox. 10dB with a little bit hum. But i think that hum is normal because i touched stripboard. Wonder why it works ok only if I touch it

I have no idea where the problem can be. Please help.
Thanks.
Cheers

[tangent]

The 5532 is a bipolar-input op-amp, not recommended with the stock CMoy design. If you measure DC offset at the output, it will be very high unless you have changed the resistor values around the chip. Here is one way to choose values:

Working with Cranky Op-Amps

It's also possible that the grounding isn't done correctly.