Two main reasons:
1) Marantz has to recoup the cost of the extra buffer stage they call "HDAMs", that are basically there to give their followers a reason to believe in them having a "signature" sound. That is a forum/hearsay myth over the years, there is no logic in believing their claims if one simply view the audio block diagram (people posted many times, I did too) and do a bottleneck analysis mentally, it's all science based opinion that me and I believe any competent EE will adopt. Also have to recoup the cost of using gold plated RCA connectors, larger case and the more artistic design, and the higher per unit cost due to the much smaller sales volume (economy of scale).
2) Their marketing somehow might have figured out that people in the USA and Canada are more easily led to believe Marantz has their warm/musical signature sound, and people in Asia and Europe might be more technically oriented and inclined to filter out some of those hypes.
2) above seems to be the main reason for the Marantz over Denon premiums to be much less significant, say comparing the Cinema 50 to AVR-X3800H, the price premium was more like between 0 (Singapore, at least at one point, and Euro 250 in Europe such as France whereas in the US in would be more like $700-$800, or $1,000-$1,100 in Canada
Such characteristics are mainly of speakers, not mid range AVRs that are typically transparent enough to not giving you the fatigue you might experienced with entry level devices especially if used beyond their rated outputs.
As long as your AVR is operating well below it's rated output, you will be fine.
About what?
Again, it is important to understand that "loud enough" or not depends on:
a) Your "taste" as you mentioned, you have your own taste, in terms of how loud you typically listen to when watching movies and listening to music.
b) The specifications of your speakers, for the Airmotiv XA2, the specs are:
From Emotiva website:
- Efficiency: 86 dB (2.83V/1m).
- Power handling: 80W continuous / 150W peak
- Recommended amplifier power: 40W or more
- Nominal impedance: 4-ohms, safe with amplifiers rated for 8-ohm loads
Note that Emotiva calls it "efficiency", that is not the right term, it should be "sensitivity".
Manufacturers rarely provide the "efficiency spec" as that spec is not typically useful for the consumers.
Based on the specs, those speakers may or may not be loud enough for you but in this case it is largely dependent on your "taste", that is, how loud do you listen to, if you want it to be as loud as what you would hear in movie cinema then the answer is no, if you are okay with say half as loud, then I would say likely "yes". More power than the AVR can offer will not help, but better/larger speakers will...
I thought we posted an online calculator for you to find out your need based on the above factors:
Peak SPL Calculator (hometheaterengineering.com)
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