Our cynical side's first assumption was that the MEElectronics SP51P core design feature, the removable backs for each bud, was a gimimick designed to make them stand out against bigger names in a crowded market. While that may still be the case, we can at least confirm they work.
Each type features a different inside, giving the sound a different environment to brew in. The "extreme bass" ports offer the largest area, while the other two narrow things down.
Surprisingly, they all sound reasonable, though the extreme bass wasn't to our taste, coating vocals and other similarly textured sound in a wallowing, low-mid goo that doesn't sound balanced or particularly natural. Kick drums cause boomy aftershocks too, telling you that these black extreme tuning ports are overdoing it a bit.
And for all the bombast of the low-end, it doesn't actually extend that far down - that sense of near-throat-rumbling sub-bass some earphones can create isn't here. Still, at this price it betters most bass-obsessed buds.
We have a sneaking suspicion that the drivers are more tailored towards the mid-level greyish tuning ports though, because overall sound quality improves significantly when they're applied. The bassy gunk is removed from the sound, like blasting a muddy tunnel with a pressure hose. Bass presence is much leaner, but clarity is significantly improved. And there's still enough low-end muscle to lend bass guitars, drums and larger string instruments the right tonality and gravitas.
Switching to the bright silver tuning ports reveals less dramatic sonic advantages. Bass takes a further step back, taking with it a little warmth from the sound. It's not sibilant and is a little more balanced than with the grey enhanced bass ports, but also a bit less fun - and a touch more fatiguing. Which you'll prefer out of the two lesser-bass ports will depend on your personal taste, and perhaps even mood, but with them the MEElectronics SP15P sound accomplished, detailed and musical - easily enough so to more than hold their own in their price bracket and some way beyond.
Lovers of bright-sounding, super-detailed earphones may be better off with the similarly metal-bodied Hifiman RE0 earphones, which offer a superior high-end and better separation, but at the price the MEElectronics SP15P perform extremely well. It's a shame that, with their tuning port concept, they're likely to appeal to basshead buyers rather than those after a more neutral "decent" set of earphones.
The MEElectronics SP51P offer three different tonalities thanks to the trio of tuning ports included in the package. Avoid the top end "extreme bass" one and you'll be laughing, with a fairly balanced, bassy and detailed sound at a good price. Metal-bodied earphones rarely come this cheap, and while the plasticy cable and cracklesome diaphragms don't exude class, these are hardy 'phones.