Hi everyone, I got given a Marantz SR4000 the other day (the 1980 2 channel receiver not the newer AV system) and I'm experiencing some distortion through both my speakers. At a low volume the sound is alright, its just when turned up beyond a low volume that it begins distorting and really gets muddy. Both speakers experience similar distortion although the power meter on one appears a bit lower (with balance in centre). I tried using my headphones too with same result. I was also using the AUX connection however I did try FM with similar results. I am fairly new to audio so any help to try pinpoint the problem would be very appreciated, I thought I would mention I do have some electrical/electronic skills so would be keen to attempt a repair if applicable! Thanks!