"Anybody explain why the Yamaha brand sells a gazillion more AVRs than the Marantz brand?"
Sure, brand recognition and availability. More people know about Yamaha A/V equipment and it's sold a whole lot more places. I can count the number of places I can buy a Marantz locally on one hand--in Southern California. I can walk into most big box stores and buy a Yamaha, or go as far as a Tweeter-level place.
It wasn't until I really started researching A/V & HT gear that I found out about Marantz, but I was aware of the Yamaha gear prior to that (and it was one of the early short-list options that lasted until the final decision).
No, not at all. The reason Marantz does not sell a gazillion and has limited distribution is because their owner, D&M Holdings, has a self designed marketing scheme to do so. Within D&M, Marantz is a stable mate of Denon and McIntosh so D&M has chosen Denon, much like Yamaha does, to bastardize the Denon brand in any/all mass distribution trade channels to generate mass unit sales/profits. Meanwhile, Marantz is their designated boutique brand in limited trade channels to maintain retail prices/margins in the boutique operations.
D&M, apparently, is banking on the perception that some people still attach some special pseudo-audiophile quality to Marantz based on bygone days with the funky, twirly thumb tuner wheel. It's all about brand marketing synergy owned by the same company to max sales -- its all perception. Marantz is probably made in their same factories as Denon.
Denon and Marantz brands have had various owners over the years; they have stabilized under the ownership of D&M with their deep pockets and aggressive business skills to give Yamaha a run for their money. According to D&M annual report, all three of their brands combined now equal the market share of Yamaha. I say good because the competition is good for the consumer. I've posted links to D&M before; you can research it and learn something.
There is nothing special in quality level of Marantz over Denon or Yamaha; they are all solid mid fi AVRs; and, I think, their SQ has improved dramatically over the last few years beginning to approach, finally, entry level audiophile stuff. When you throw in the AVR features/needs of lip sync, HDMI, room equalization, etc. plus the very good stereo SQ, all these brands have a lot going for them.
FWIW, at least one forum member on this thread has posted that the SQ of the new Marantz AVRs has changed and gone south.
Most treble units in ordinary speakers come in at around 2khz. In 3-way systems where there is a dedicated midrange unit, they usually cross over around the 4 - 5 khz mark.
Yamaha's have the reputation as bright because their poor power supplies are usually driven to hard by HT or music enthusiasts trying drive inefficient or difficult loads to ridiculous volumes. I have not experienced more brightness from Yamaha properly driven than Denon.