During the past 15 months or so, I have been working from home. In my "home office," I set up a makeshift stereo system. It consists of a (previously neglected) 17-year-old Yamaha entry-level home-theatre receiver (used in stereo mode), a pair of Fyne Audio F300 bookshelf speakers, and an iPOd Touch and an iPad as a source (streaming Tidal and Spotify). For the past two weeks, I noticed that the sound has become a bit muddy. It is as if the high frequencies were truncated. I checked all the cable connections, and they were fine. The speakers are at the exact same place as before. I sit in the same spot (at the desk), and so listening positions are not an issue. So I am wondering what is going on. I realize that this may just be in my head. The sound might have been like this from the start. But I would just like to know if it could be because the receiver is getting old. As mentioned, the receiver is a 17-year-old Yamaha. Back then, Yamaha receivers were not known for warm sound. The sound should be brighter than what I am hearing. Thanks.