Thank you very much for the non polarized capacitor advice, I will try it with a pair of RCA x33av speakers, and I hope it works with the headphones too.

I emailed Kiwa electronics two weeks ago asking if they have in mind or in a near future an audio upgrade for Drake R8 series.I have still not received response. I explained to them the problem and as I have read in some forums that many owners have it too.
I hope that the Kiwa consider it.
I made the Kiwa audio upgrade on the Degen 1103 and the difference it is amazing.

Meanwhile I will keep the Drake until I find a solution.

Thank you very much