Google is your more reliable friend, not dealers, reviewers and forum people like us. But even your more reliable friends, such as Google, you have to be careful reading what you find. For example, if the author(s) don't appear to have more than the basic scientific knowledge in the topic(s), leave them alone and go with those that appear to have the knowledge, and believe in science instead of hearsay. Or if they are biased, such as written by someone who obviously have vested interested in promoting certain gear, while pretending to say things based on science by throwing around some seemingly technical jargon. The dealer talks about the Marantz warmth are expected because a) as HD pointed out, b) they may actually believe it themselves, based on hearsay and groupthink in the audio circule/industry, c) it's easier for them to agree with you, so you don't focus on the speakers they sell, but your amps, receivers etc..
Think about the power (and how it works) of hearsay for a moment, using your own thread as an example, you started talking about the Marantz warmth yourself! So, if we don't give you some counter points, but instead, agreeing, especially if we had a few Marantz devices ourselves, then other readers would read the posts and might become part of the big hearsay/groupthink generator; and the Marantz warmth belief would eventually become the "truth" over time, when it should have been more correctly considered a "myth" by that time. That's could well be how it actually happened over time! Though in the beginning, like 50 years ago, it probably was true to some extent, that Marantz had designed some tube, and then SS gear that would sound soft, dull, dark, with high frequency roll off, could have been achieved via intentional or unintentional lower damping factor than the average at the time.
Disclosure: I owned, still own multiple Marantz devices, among a few others I have also owned/still own. They (mine) are all transparent, it's the speakers and the room that determine the bright, warm, neutral "sound", assuming the media recording/mastering about neutral.