After receiving the ad900x and using them right out of the box,then letting them burn-in for a day at low volume,i can say that any mention of poor bass quantity,poor low end extension or any other adjectives used to describe any type of missing bass,....is totally incorrect. In fact,my first impression was,wow,this has too much bass.(although not really,it's all there,bass,mids and treble)
I will say one thing though,Audio Technica's thoughts on who exactly is going to wear their HPs must be Stewie Griffin from the show Family Guy. I mean this literally,someone with a big,football(american football) shaped head that's pointy on the sides where your ears are,and this is coming from someone with a big,german head(but normally shaped). This is probably the only way your going to get the proper seal and I have no doubt(because I tested) it affects bass.
Upon initially putting on these HPs,i instantly noticed that there was a gap in the upper most part of the pads right above my ears. I could actually easily wiggle my finger into this gap. When I pressed the cups against my head to seal the gap,the sound became fuller and the bass instantly became very present and very impressive.
I suppose I could have bent the two supporting,arching bands(which,by the way,are not cheap plastic tubes that i've noticed on other HPs but in fact,seem to be solid metal bands encased by polymer,..that's my best guess based on gently feeling them) to better seal the cups on my head but I totally decided against that and simply put a fairly long rubber band between the two wings,so that the two wings better support the HPs,and that instantly perfected the seal and the sound. Problem solved,full stop..........perhaps not worthy of a HP of this caliber but there it is.
I'm still undecided about keeping them or not(simply because of the fit issue above) but i'm leaning towards keeping them because of the SQ and otherwise the construction and materials are very good. I also love just looking at the open back part,..but,ultimately,it's the SQ that counts and that part is impressive. Thus far,I've used them for several music tracks i'm very familiar with,a movie and several programs and the sound stage,airy,imaging,detail and extension(both high and low) are very good. The bass can be felt when it's in the music or movie but not when it's not supposed to be there. These are very,very detailed but not in an extremely analytical,dry way and with no veil. They are also neutral but with very slight colorations here and there that seem to add instead of substrate. The highs are very interesting,they give me no sibilance and yet they are very present all the time,with good extension,giving me all kinds of detail. The mids are all there in full with a slight coloration that's very attractive(I was worried that the mids would be too forward,they are not,..but also nowhere near hollow). the bass extends well(I can clearly hear sounds in the 30Hz region,if it's there in your music) and explosions can be felt(but not excessively,if that's what you would prefer). the bass is full but I feel that it lacks a bit of finesse,just slightly muddy but also lush,tight and with a slight emphasis in the mid to upper region. The timbre is good,but,and i'm having a hard time describing this,with just slight colorations here and there.
anyway,a very enjoyable SQ. by the way,these can EQ fairly well if you want although I didn't for my evaluation,..but you can EQ then till your ears bleed from excessive highs if you want,..the bass also seems to respond well. also,specific SQs from your particular amp aside,these don't seem to change that much from amping or just using your desktop computer(I don't use portables) but I did notice that,when using my 20something year old Pioneer VSX D1S,that the sound became slightly fuller,low end extension was slightly better,sound stage and imaging seemed slightly better,...but I think someone without an amp will like these fine. again,i don't use portables of any kind.
please take my review here with a grain of salt. all ears are different and I've also not had this ad900x for a very long time.
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does anyone know if the JDS Labs Objective2 amp has a very neutral sound? what about when adding their dac? what's the difference you notice with and without dac?