ø9mm + 2 × ø7mm Dynamic Drivers


The FONGE brand has been releasing dirt-cheap earphones for a long time now, and are probably the #1 source for QKZ's rebranded earphones. Their SD-01 model, more widely known as QKZ CK10, is an interesting one.

The earphones resemble my most adored bass-monsters, the I-INTO i8, but they do not share the same housings at all: the SD-01 are clearly longer, taller and thicker, making them way too bulky than necessary. The i8 are "compact" in comparison, despite weighting about the same. The drivers, of course, are completely different.

The cable, however, looks and feels a lot more durable than the one on i8, but some might say that it also looks cheaper because of the pretentious golden parts.

Ultimately, when we take sound quality into account, everything else seizes to matter. The i8 are miles better at keeping a rather neutral and clean mids, while the SD-01 are dark and harsh, despite the fact that both of them are very bassy earphones.

So if you're looking for a true basshammer, don't waste your time on these. Get a i8 instead, thank me later.

Also known as: QKZ CK10


  • Monsterous bass rumble for the crazy bassheads among us. It's impressively stable even at higher volumes.
  • Overall good build quality with enough metal parts to make them look more impressive than they really are.
  • Quite a nice cable, very unlike most previous FONGE (or QKZ) earphones.


  • Dark and harsh mids and highs resulting in discolored vocals and instruments.
  • The heavy bass bump can be exhausting. It's even heavier than I-INTO i8's bass.
  • Big and bulky, will be a hard fit for smaller ears.
  • A cinch on the cable could have been invaluable.

Package & Accessories

Ear Tips - Single-Flange:

S+2×M+L, grey (translucent), ø4mm red bores


Black + red, rectangular, generic

Build & Materials


Plastic (glossy) + metal*, ø6mm nozzles (ø4.5mm bores), riggid strain reliefs


Plastic (matte), single-button


Metal, stiff strain relief


Silicone (braided), 122cm, extra-soft, straight


Metal, straight, long, stiff strain relief

Comfort & Fit

About the same fit and wearing style as the I-INTO i8, but the housings are bigger and bulkier, which makes them less suitable for small ears. Moreover, the included tips are poor, to say the least, and getting a proper seal with them was too much of a trouble, so I had to use some softer tips instead.

Lows / Bass

The bass is as you would expect - massive. The sub-bass is as powerful as what the human ear can handle, if not more so, and the bass rumble is hard to miss. This is good news for the bassheads out there, but bad news for those who can't bear such power. The good thing is that the bass remains quite stable even at higher volumes, in case you're planning to blow your eardrums out with some dubstep, drum & bass or trap music. It is as overwhelming as I expected it to be.

Mids / Vocals

There mids are there and they aren't affected much when the bass hits, but that's where the good news end. The mids are completely discolored - vocals are dark and harsh, instruments are completely inaccurate and off-pitch, and on higher volume the harshness exposes shrilling sibilance. It's torture for my hearing, but I've heard worse.

Highs / Treble

The highs are as "good" as the mids, and share the same problems. Underwhelming level of detail, inaccurate instrument reproduction, especially cymbals and high-hats that sound like samples of white noise, rather than actual instruments, and so on. Truly unworthy of your attention or money.

Frequency Response

Published on 2020-10-25 19:58:16 (GMT)