First of all, thank you guys for this awesome thread, it is based on measurements and facts, not someone's "this are bass monsters, blah-blah, I can't hear you". I was lurking the thread for a month, finally ordered sz-2k, waiting for the tenso's shipment for now. I use Sony NWZ-e474 as DAP (me thinks Clear Bass will come in handy with sz-2k) and Fiio E07k as amp (it is a bit weaker than E17 in amp section), how do you think, is this enough for sz-2k to produce hard hit or I'll definitely need Fiio E17\E12\better amp? Saving for 77x right now, it's kinda hard for a student in my country to afford all this cans at once (*crybaby mode on). I can record bass paper test with my NWZ\E07k when sz2k will arrive (if anyone needs this).
Got my SZ-2000 today, they are really awesome! This headphones just made me laugh, and this was laughter of happiness ! Stock pads are meh (why in the world JVC would sell their "premium" model with this pads, i dunno), unfortunately Superlux HD669 pleather pads are not working with these - they just don't stay in fixated position, waiting for my 77x now.
Last year, I tested all of the hyped budget-fi in-ears to find something better than the Sennheiser CX500, and was disappointed by each one. I concentrated on in-ears because prior to that I was recommended the Grado SR60 and the Sennheiser PX100 for basshead full-size cans, which made me believe the skewed assumption that full-size headphones aren't efficient enough to drive low frequencies at high volumes like in-ears can (borrowing my cousin's Sennheiser HD598 and HD555 and immediately distorting them with my bass test strengthened that position).
When I tried to complain, I was met with derision. "You spent time at head-fi and this is what you learned from there?" "Bass quality is not the same as bass quantity."
"Why would you even do this distortion test?" "Are you joking?" I, as a hardened debater, held my ground. I wanted something so simple and so straightforward--maximum bass SPL before distortion--and it was mind-bogglingly difficult to even discuss that without getting derailed by elitist logorrhea.
This year, after my ears started hurting after only an hour of listening with in-ears, I tried to look for non-canal alternatives and thought of giving full-size cans another chance. That's when I saw Hawaiibadboy being all confused at the Basshead Club, as if the whole world were lying to him lololol!
So, yeah.
So, do WE* only care about bass quantity and not quality? First of all, what is "bass quality"? There is a long list of adjectives in the audiophile glossary to describe bass. Science and engineering forums however
argue that terms like "speed, depth, slam/impact/attack, detail, extension, tightness, presence, balance, realism, control," etc. are more easily explained by frequency response graphs, or
"magnitude plots based on gain, Q, and frequency of each resonance." In other words, (and room reverberations aside,)
"It sounds the same if EQ'd the same." As I said in
here, while EQ seems like a magical tool, it can't correct room reverb. Imagine listening to your headphones through toilet paper tubes. The resulting echoes through the tubes are nonlinear, and EQ is only a linear filter. Closed headphones without damping material inside the cups are prone to room reverb that may be unfixable by EQ. The same EQ argument extends to overall sound quality. If you don't use EQ for any reason, that is completely fine. But you should at least be informed of how mechanical engineers achieve a certain frequency response
through diaphragm shape (also see
here). So, no, we don't just care about bass quantity, we also recommend the use of EQ to achieve your desired "sound quality." You will also need EQ to raise the bass volume to how loud YOU want it without being deafened by the more sensitive frequencies.
As for caring ONLY about quality and NOT quantity, I'll just quote myself: "In a signal reproduction perspective, it is important for transducers to be capable of accurate reproduction at high gain. Using the hearing loss argument is just an excuse. 'We didn't design the headphones to be able to reproduce a front row rock concert experience because it's bad for you.'--even if this was a sincere concern for my health, and not a lame rationalization of incompetent engineering, one should still respect the end user's agency."
Anyway, here is a troubleshooting guide if you think you're not getting enough bass from the SZ:
- Is the SZ distorting? If not, EQ (we'll help you! It can be tricky, and we're still finding a general solution for Mac and Android. I think Hummel and Milk figured out a solution for Mac). If yes, go to next step.
- Is the bass volume 127dB loud (the loudest recorded human scream is 129dB)? If yes, then you're most likely used to louder bass in car audio (we're hoping that headphones reach that level too). If not and it is already distorting, go to next step.
- Is your source or/and amp distorting the signal? The easiest way to test this without measuring the signal directly with RMAA/REW is to use different sources, amps, and headphones. When I first got my SZ, I only had a Fiio E5 (max output 108mW at 15Ohm) and I thought the SZ could only go a bit louder (+5dB in rap tracks) than the 77X before distortion. After I got the Fiio E12, the SZ reached +16dB louder than the 77X. If the SZs are still distorting with a powerful, clean amp, you most likely got a defective pair.
*By WE I refer to all of us who love extreme bass.
As for the pads, here is 
