I picked this up today with the matching preamp, when I got home I plugged the amp in and it was in protection mode. I blew out all the dust with air and then hooked it up. the unit played for awhile then the right channel went out then in protection mode. it did sound a little muddy but it may have been my grade advents. Is there a common problem with them. I did see people replacing the 4 large caps on them.