I'm really curious how this Marantz 80 watts compares to NAD 50, but expect it to be less in reality based on weight/cost.
You have a point, for a 5 channel model, your 50WX5 NADT743 is very heavy and is conservatively rated. That said, sometimes people (not referring to you)get carry away bragging how their NAD or HK model's conservatively rate their products and forget that there is a point where you have to consider $/watt. Here are some lab reports from a HomeCinemaChoice, a British AV magazine:
NAD743 £400
Manufacturer’s Rated Output
5 x 50W into 8Ω
Measured power @ 1kHz
2ch driven: 75W into 8Ω
5ch driven: 55W into 8Ω
Fidelity firewall @ 1kHz/2ch
70W: into 8Ω (0.05%THD)
Distortion @ 1kHz
0.008%THD @ 50W (8Ω)
Frequency response
20Hz-20kHz +/-0.025dB
36.1 lbs
Denon 1804 £400
Manufacturer’s Rated Output
5 x 90W into 8Ω
Measured power @ 1kHz
2ch driven: 110W into 8Ω
5ch driven: 35W into 8Ω
Fidelity firewall @ 1kHz/ 2ch
105W:into 8Ω (0.05%THD)
Distortion @ 1kHz
0.002%THD @ 50W (8Ω)
Frequency response
20Hz-20kHz +/- 0.02 dB
26.2 lbs
Marantz SR4400 £350
Manufacturer’s Rated Output
6x 90W into 8Ω
Measured power @ 1kHz
2ch driven: 110W into 8Ω
5ch driven: 85W into 8Ω
Fidelity firewall @ 1kHz/ 2ch
105W:into 8Ω (0.05%THD)
Distortion @ 1kHz
0.005%THD @ 50W (8Ω)
Frequency response
20Hz-20kHz +/- 0.14 dB
27.5 lbs
Onkyo SR501 £300
Manufacturer’s Rated Output
6x 65W into 8Ω
Measured power @ 1kHz
2ch driven: 80W into 8Ω
5ch driven: 35W into 8Ω
Fidelity firewall @ 1kHz/ 2ch
75W:into 8Ω (0.05%THD)
Distortion @ 1kHz
0.01%THD @ 50W (8Ω)
Frequency response
20Hz-20kHz +/- 0.05 dB
21.6 lbs
Sony DB790 £300
Manufacturer’s Rated Output
6x 90W into 8Ω
Measured power @ 1kHz
2ch driven: 96W into 8Ω
5ch driven: 65W into 8Ω
Fidelity firewall @ 1kHz/ 2ch
95W:into 8Ω (0.05%THD)
Distortion @ 1kHz
0.004%THD @ 50W (8Ω)
Frequency response
20Hz-20kHz +/- 0.05 dB
31.9 lbs
You can see that when compared on $/watt, 2 channel output, fidelity firewall output, the T743 offers no advantage against other similarly priced reputable products. In fact the Sony and Denon earned the bestbuy rating in a shootout with the Onkyo, JVC and Marantz. Both models offer significantly higher 2 channel output rating than the NAD. If you read some of the Audioholic articles, the ACD rating is not as important as we sometimes think it is.