Well every headphone has its cons and pros but Q40 do a lot of good for the price for some1 who's looking for a serious amount of boosted bass.
Pros:
- Extremely good quantity vs quality bass output ratio for the price (unbeatable)
- No excessive or very low midrange and highs ringing / resonances throughout the entire range, especially the often troublesome upper-midrange is very well controlled and female vocals and acoustic guitars etc remain very clear & crisp. Lows has a bit higher amount resonances like every headphone but nothing too bad but concidering there's no dampening in the back that's to be expected but honestly I don't want it damped, for me it's just right, too "dry" bass output is also boring for me.
- Good tonality, balanced midrange vs highrange, no excessive dips or peaks (slight peak around 9kHz which settles in with burn in or can be padmodded to be solved).
- Very engaging forward presentation; for people who prefer that up-front sound
- Responds well to amping; more dynamic sound, more forward and fullbodied midrange, better bass.
Cons:
- Build quality not the best but acceptable
- Clamping a bit higher than average; can be either good or bad depending on person (I personally like the clamping and haven't had any issues with it, I've worn it for hours a day since I got it without needing of stretching etc). I'm using the stock pads with papertowel inserts behind the pads, the stock pads are shallow but works well with the tight clamping. For example with Beyerdynamic DT770 Pro the more compact pads caused wearing fatigue for me, these don't (worth pointing out that the stiffness of the pads are always extremely important, stock ones are shallow but quite soft still)
- Soundstage size is about average/slightly below average for a closed headphone
- About average imaging, the positional cues aren't always superclear but most of the time they are there (I recommend using my custom foobar2000 dolby headphone config and that issue is a thing of past with any headphone).
- Highs extension not the best, so it lacks a bit "airiness" if you're into that
- A bit of smearing and hollowness in the midrange unless amped properly
