If you want a multi-armature in-ear monitor with a three-way crossover, choose CCA KZ AS16; if you need a hybrid driver setup with interchangeable 3.5 mm and 4.4 mm plugs, choose EPZ P40. For side sleepers comparing these wired in-ear options, I’d lean toward the CCA for its stated ergonomic fit and sound isolation, while the EPZ’s connector flexibility is its clearest advantage.
Neither is an open-ear design, so neither is the best open ear earbuds for side sleepers. These are in-ear monitors; the choice comes down to fit priorities, driver design, and how you connect them.
If you want a multi-armature in-ear monitor with a three-way crossover, choose CCA KZ AS16; if you need a hybrid driver setup with interchangeable 3.5 mm and 4.4 mm plugs, choose EPZ P40. For side sleepers comparing these wired in-ear options, I’d lean toward the CCA for its stated ergonomic fit and sound isolation, while the EPZ’s connector flexibility is its clearest advantage.
Neither is an open-ear design, so neither is the best open ear earbuds for side sleepers. These are in-ear monitors; the choice comes down to fit priorities, driver design, and how you connect them.
• CCA KZ AS16’s biggest strength: 16 balanced armature drivers and a three-way crossover; trade-off: it’s wired and offers a 3.5 mm connection rather than interchangeable 3.5 mm and 4.4 mm plugs.
• EPZ P40’s biggest strength: a hybrid arrangement combining two dynamic drivers, one planar driver, and one piezoelectric ceramic transducer; trade-off: its more varied driver setup may be more than a buyer needs if the priority is a straightforward in-ear monitor.
• CCA KZ AS16 fit: an in-ear shape with a claimed ergonomic design and sound isolation; the sheet does not provide measurements or a specific side-sleeping profile.
• EPZ P40 fit: an ergonomically designed cavity made with skin-friendly resin; the sheet does not specify how far either earbud protrudes from the ear.
• Choose CCA KZ AS16 if you want a multi-armature configuration and a 2-pin cable you can replace or adapt.
• Choose EPZ P40 if interchangeable 3.5 mm and 4.4 mm plugs are useful for your audio gear.
How We Research
We compare products from their published specs and features; the verdicts below are our independent editorial opinions.
Updated: 2026-10-22 · 6 min read · Independent comparison
This is the more direct fit for someone who specifically wants a multi-armature design, a wired connection, and a detachable 2-pin cable. It comes with a silver-plated cable, and the 2-pin connection can be used with replacement cables or Bluetooth adapters. The listed connector is 3.5 mm, so it suits a device with that jack unless the listener adds a compatible adapter.
For side sleepers, the in-ear placement and stated ergonomic design may make it more relevant than an open-ear product, but the sheet does not establish that it will be comfortable against a pillow. It also gives no housing dimensions or profile information. I would skip it if you need wireless listening without an adapter, or if you specifically want an interchangeable 4.4 mm plug included as part of the connection setup.
The EPZ P40 takes a different route: two dynamic drivers, one planar driver, and one PZT ceramic transducer. The product description positions the ceramic driver as a way to add high-frequency detail, while the listed frequency range is also 20–40,000 Hz. Its impedance is 14 ohms and its sensitivity is listed as 100 dB. Those figures describe the product, but they do not by themselves establish how it will sound with every source or listener.
Its standout practical feature is the interchangeable 3.5 mm and 4.4 mm plug, paired with a 0.78 mm 2-pin connector. That offers more connection options than the CCA’s listed 3.5 mm jack. The P40 is also described as having an ergonomic cavity made from skin-friendly resin, with a CNC-processed metal faceplate. It is still a wired in-ear monitor, not a wireless or open-ear model.
For a side sleeper, the ergonomic design is a potentially relevant point, but it does not guarantee that the shell will stay comfortable when pressed by a pillow. The product sheet gives no fit dimensions or sleep-specific design details. I’d pass on the P40 if your main goal is the CCA’s 16-balanced-armature configuration, or if you want a product whose documentation specifically addresses low-profile use while lying on your side.
• Best for a 16-balanced-armature design → CCA KZ AS16. It lists 16 balanced armature drivers and a three-way crossover, making that architecture its central distinction.
• Best for a mixed driver arrangement → EPZ P40. Its configuration combines two dynamic drivers, one planar driver, and one PZT ceramic transducer.
• Best for swapping between 3.5 mm and 4.4 mm plugs → EPZ P40. Its included connection system is described as interchangeable between those plug types.
• Best for a 2-pin cable you can replace or adapt → CCA KZ AS16. It uses a 2-pin design and includes a silver-plated cable; the product description also notes compatibility with Bluetooth adapters.
• Best fit for someone seeking stated sound isolation → CCA KZ AS16. Sound isolation is listed in its design description. That is not the same as active noise cancellation.
• Best fit for someone drawn to a resin-and-metal appearance → either, for different reasons. CCA combines transparent resin and metal; EPZ pairs resin with a textured CNC metal faceplate.
• Best sweat resistant in ear headphones for side sleepers → neither can be confirmed from these specifications. Neither sheet provides a sweat-resistance rating, and neither is described as an open-ear design.
• Best for side sleeping based on the available fit details → no definitive winner. Both are in-ear models with ergonomic claims, but neither sheet specifies a low-profile housing or pillow-comfort testing.
I’d choose the CCA KZ AS16 if I wanted the more clearly specified multi-armature setup, its three-way crossover, and stated sound isolation. The EPZ P40 is the stronger pick for someone who needs both 3.5 mm and 4.4 mm plug options. For side sleepers, I would not call either a sure fit: the available details do not establish how comfortable either shell is against a pillow. I’d choose the CCA for the overall design priorities described here, while treating side-sleep comfort as an unanswered fit question.
FAQ
No. Both are wired in-ear monitors. If you’re searching for the best open ear earbuds for side sleepers, neither matches that product category.
The EPZ P40 combines dynamic, planar, and PZT ceramic drivers. The CCA KZ AS16 uses balanced armature drivers, with 16 listed in its configuration.
The specifications do not establish a clear winner for side sleeping. Both are in-ear designs with ergonomic claims, but neither provides housing dimensions or a specific low-profile sleep design.
The EPZ P40 is the straightforward choice because it is described with interchangeable 3.5 mm and 4.4 mm plugs. The CCA KZ AS16 lists a 3.5 mm jack.
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