Hi Elara,I´m having the same problem with my HK6500.After recap of my amp, the sound is dull, just bass frequencies are ok, as it was before.I used Panasonic FC and Nichicon UPW series caps.Could you give me an advice, how to sort it out?Strange thing is, that when I turned it on after recap, it sounded dull, then after 5 hours of playing it was nice and now after 30hours it´s muddy sounding again.Thank you .Jan.