What I’m saying here is that it’s better to own three $100 headphones than one $300 headphone. Or three $300 headphones than one $900 headphone. Why? Because most people don’t limit their playlist to strictly one genre. And following the logic from Rule #2, the right headphone-music pairing is going to be better than one expensive headphone paired to the wrong music.
A: Absolutely not... unless you're just looking for an excuse to try something new. But if you're not made of money, you can always hit up the manufacturer for a pair of replacement tips. Most earbuds only come with one set of each size, so losing one can be annoying. If you're in an experimental mood, Comply offers aftermarket tips that fit your brand and come in a variety of materials.
That amp, if in good working condition, has 100 times the potential sound quality that those 2 headphones can play. You could improve the sound somewhat with a careful EQ, since the Marantz will have power reserve to spare. But I’d try to find a better headphone, and there are some bargains out there. If I were suggesting an ortho, I’d say get the lower price Mad Dog, which will give you great audiophile sound with the Marantz.
The moving coil driver, more commonly referred to as a "dynamic" driver is the most common type used in headphones. It consists of a stationary magnet element affixed to the frame of the headphone, which sets up a static magnetic field. The magnet in headphones is typically composed of ferrite or neodymium. A voice coil, a light coil of wire, is suspended in the magnetic field of the magnet, attached to a diaphragm, typically fabricated from lightweight, high-stiffness-to-mass-ratio cellulose, polymer, carbon material, paper or the like. When the varying current of an audio signal is passed through the coil, it creates a varying magnetic field that reacts against the static magnetic field, exerting a varying force on the coil causing it and the attached diaphragm to vibrate. The vibrating diaphragm pushes on the air to produce sound waves.

Communication headsets are used for two-way communication and typically consist of a headphone and attached microphone. Such headsets are used in a variety of professions as aviation, military, sports, music, and many service-oriented sectors. They come in all shapes and sizes, depending on use, required noise attenuation, and fidelity of communication needed.
One thing I suggest to prospective customers for a specific headphone, if I have that headphone on hand, is for them to suggest 2 or 3 music tracks by a particular artist and composer that I can sample on that headphone, not so much for me to suggest how it sounds, but mostly to check if that headphone has any real sonic issues with that music. For example, a headphone that’s ideal for classical and acoustic music might sound too harsh with metal and industrial goth.
Gaming headsets are headphones that have a microphone attached and allow users to speak to other people and hear them with the same device. In fact, gaming headsets have other practical applications as well. You can use them in business or personal situations when you want to speak to people on a computer using a video phone program or social media chat room. Although these work for music applications, they're more suited for conversational clarity.