Wow. I'm really sorry that you felt like you went backwards in some ways with the Marantz. When I tested the 8805 in my system, I was using all my very high end power cords and interconnects and everything. The only thing I did not do was upgrade the fuse in Marantz to a Hi-Fi Tuning silver (which is something I would have totally done). We only had the Marantz in my system for one afternoon. When I say "it had good impact", I mean it had good punch in the midbass and midrange impact. A good amount of punch-you-in-the-chest impact and stuff like snare drums hit with authority. The high frequencies were definitely rolled off, but it was not that bad. Your situation could be from stock fuse and power cords and stuff. It could also be that your using the previous owner's Audessey setup, and I would love to hear if this was the case. Doing a factory reset is always a recommended thing because you don't know what the existing configuration is doing to your sound. That being said, I will make comments based on what you're hearing now.
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So, I guess the first question is to whether or not you want to work with the Marantz to try to get it to sound better. This could be just adding a silver fuse into the Marantz. But it could also mean you need to upgrade the power cords and possibly the interconnects. This could mean spending hundreds of dollars on "tweaking your system for the Marantz". We just won't know until we get there - doing one step at a time.
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When you say you "kept feeling like you had to turn up the volume and had to strain to hear certain things", I think I know what you mean. If the equipment is too warm/slow sounding, it will cause the upper midrange and highs to become too soft and laid back. This will prevent the more subtle sounds from cutting through, especially when there is a lot of different sounds going on, and you may not feel you're getting the full impact of sound crispness and clarity and sharpness.
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The first tweak for the Marantz (if you want to try working with it) is to upgrade the fuse. Do you feel comfortable taking off the top cover of the Marantz? It's very easy. The top cover can be removed just by removing the screws that hold it in place. The fuse or fuses should be on a small board that is very close to the power cord socket. On these processors, it is usually a small fuse, but you should check. If the fuse is less than 1" long, then it is the small 5x20 size. If it is longer than 1", then it is the large 6.3x32 size. Parts Connexion is selling the older Hi-Fi Tuning Silverstar for 60% off - $16 for a small fuse. They have a couple of the 1.8A left (I recommend getting a 2A fuse if possible). This silver fuse should improve the clarity and impact a good amount. If this doesn't get you all the way, we can still upgrade the power cord as well, which will make a difference too. The goal would be to get as much silver elements into the power supply system as possible. Please be aware that the silver fuse will require a 7-10 day burn-in before it settles down.
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So, I guess the first question is to whether or not you want to work with the Marantz to try to get it to sound better. This could be just adding a silver fuse into the Marantz. But it could also mean you need to upgrade the power cords and possibly the interconnects. This could mean spending hundreds of dollars on "tweaking your system for the Marantz". We just won't know until we get there - doing one step at a time.
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When you say you "kept feeling like you had to turn up the volume and had to strain to hear certain things", I think I know what you mean. If the equipment is too warm/slow sounding, it will cause the upper midrange and highs to become too soft and laid back. This will prevent the more subtle sounds from cutting through, especially when there is a lot of different sounds going on, and you may not feel you're getting the full impact of sound crispness and clarity and sharpness.
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The first tweak for the Marantz (if you want to try working with it) is to upgrade the fuse. Do you feel comfortable taking off the top cover of the Marantz? It's very easy. The top cover can be removed just by removing the screws that hold it in place. The fuse or fuses should be on a small board that is very close to the power cord socket. On these processors, it is usually a small fuse, but you should check. If the fuse is less than 1" long, then it is the small 5x20 size. If it is longer than 1", then it is the large 6.3x32 size. Parts Connexion is selling the older Hi-Fi Tuning Silverstar for 60% off - $16 for a small fuse. They have a couple of the 1.8A left (I recommend getting a 2A fuse if possible). This silver fuse should improve the clarity and impact a good amount. If this doesn't get you all the way, we can still upgrade the power cord as well, which will make a difference too. The goal would be to get as much silver elements into the power supply system as possible. Please be aware that the silver fuse will require a 7-10 day burn-in before it settles down.