While my initial answer was "in jest" there are a couple things that might be valuable toward your goal of a more complete and detailed sound, that "cupping" offers.
Keep in mind the sonic you hear from cupping is due to two mechanisms. First you are collecting and directing more DIRECT SOUND into your ears and SECOND, you are blocking or reducing reflected sound from the sides and rear.
1) The first thing you need to consider, is that "reflected" sound (that which is not DIRECTLY from the speaker to your ears) will muddy and distort everything you hear. So absorption is ALWAYS a good thing toward the goal of clearer, precise and accurate sound. ANY sound you hear that is reflected will ALWAYS be a distortion of the recorded signal and thus not be accurate. So reducing any and all reflections will move you toward your goal of purity.
2) You likely will not be able to stop all reflected sound so moving more nearfield will also help you. When you move nearfield your ears hear the signal before it disperses as much. That is, the signal is louder. As sound moves away from the speaker driver, it "expands" (disperses) and the energy is reduced the further away you are from the source. As well this dispersed sound eventually becomes reflected sound off of room surfaces, and completely muddies and distorts what your ears collect.
What you are hearing, (or wanting to hear) is similar to the purity of sound you hear with headphones. Why are phones so detailed? NO REFLECTED ROOM SOUND, and undistorted, pure signal directly to the ears. But the problem with phones is spatial cues. NO Soundstage.
Many people misunderstand (including sound engineers) what occurs and the goals in a 2 channel system, compared to a live venue. The goals are NOT the same, and using the same physics will not work to your advantage.
I might add that while putting larger reflective surfaces immediately behind your head will give you a bit of what you want, they are not as good a solution as above. The Pinna is a collective mechanism, and is of a material (skin and cartilage) that doesn't reflect much. It directs sound to the ear canal.
3) If you have a set of headphones, try placing them "BEHIND" the Pinna, so that it causes the Pinna to "stick out" more. This simple change can give you (along with the nearfield suggestion above) much of the sonic you are after at NO COST.
