1. I've tended to prefer sound of yamaha over denon....They dont have the 5100 yamaha anymore only the 5200 model.
2. I'm a bit shocked my marantz needs to be above 80 on sound bar for volume...
1. I think built-quality of the Yamaha 5100/5200 is better than the AV7705 and closer to the AV8805. Here are some measurements and specs from S&V for the 5100 and 8802:
Yamaha CX-A5100 $3K MSRP, 29.8LB (S&V):
SNR 130.92 dBA, Crosstalk 93.82dB 1kHz, THD+N 0.008% 1kHz, FR 20Hz-20kHz -0.01dB to -0.02dB
Marantz AV8802 $4K MSRP, 30.6LB (S&V):
SNR 130.38 dBA, Crosstalk 92.21 dB 1kHz, THD+N 0.008% 1kHz, FR 20Hz-20kHz -0.04dB to -0.01dB
Unless you must have Audyssey XT32, I would rather have the Yamaha 5200 than AV7705.
2. If you don't want to have to turn up the Master Volume so much, just increase all the Speaker Channel Levels. For example, if the Speaker levels are set to 0.0, increase them to +3.0, +4.0, or +5.0. Otherwise, don't worry about the Master Volume since it doesn't mean anything important.
3. Or just wait for the next generation of Yamaha pre-pro (probably CX-A5300).