Here's my initial impressions and I know I've not even allowed for any potential burn in time yet but from my experience headphones only get better with time. Whether it is burn in or our ears getting accustomed to the signature or both is a matter of opinion.
Out of the box.
The Q701 comes in a package that pales in comparison to the X1. There really is no contest. The X1 box and internal packaging is leagues ahead in premium materials and quality.
The Q701 build quality appears to be fine but it's nowhere up to the RRP it commands. I rate the build quality slightly lower than my last Sennheisers, the hD598 as the plastic feels lighter and thinner. The headband doesn't feel like real leather, it's thin and unlike the calf leather band on the X1.
My Q701 creaks if you hold both cups and expand the headband by pulling them away from each other. This is due to the extended rod tracks stuttering along the headband. The silver bits on each side of the headband also creak. They are not metal but more a polycarbonate/plastic like material.
The Q701 is lighter than the X1.
The earcups are larger than the X1, I actually prefer how large they are, they comfortably surround my ears. The earpad padding is nice, it's thicker on one side of the cup to better cover around your ears at the back of the head.
The headband extends to it's maximum on my head. I don't have a large head but if I hold the headphones on my head the cups just sit in the middle of my ears so for my head at least they're the right size at maximum extension.
The headband dimples are spongy/hollowed out so do compress in but even so after an hour I can feel them on my head pressing in and causing some discomfort. The foam strips from Amazon have not arrived yet. Contrary to one suggestion from one of our fine members, I will not be using sanitary towels in the mean time ¬_¬
Lastly the headband clamping pressure cannot be adjusted and it clamps quite tightly on my head. I expect this will loosen over time. The X1 can be adjusted in this regard.
The cables are fine although not as nice and lightweight and good feeling as the V-Moda cable on my X1. I actually won't be DIY modding the longer one of the two to 1.7m as I had planned out. Guess I'll keep the DIY bits I bought as spare for something else. The cable isn't as thick or as heavy as the pictures online otherwise suggested.
Sound quality.
I played back a mix of everything from 24/96 Flacs to normal and mp3s. I noticed a consistent bias in the mids and high and because the soundstage is so wide I got the feeling of the vocals and instruments like guitars "popping" around me, maybe pop is the wrong term to use but they had quite a lot of extra life from the different signature.
The bass is less than on the X1, nobody would ever expect anything different here though
The X1 signature focuses on lows and mids with balanced highs. The soundstage is wide but the Q701 is just wider and the signature suits the soundstage perfectly. Playing on the Q701 for a few songs then playing them on the X1 again I actually preferred the signature of the Q701. The X1 is beautifully warm and the bass is deep and detailed but the Q701 has a different feeling. I don't want to sound weird when I say this but the Q701 sounds more intimate and the details in the background instruments are subtly more present.
I said before that on the X1 the bass detail pops and you are then engaged.especially in the mids/lows area. On the Q701 I feel engaged more on the mids and highs with detailed bass but not as deep as the X1.
There is a hint of sibilance on them, I expect this will settle in time. The HD595 and 598 both had the same feeling of sibilance which settled over regular use. They are certainly sharper sounding than the X1.
Music I especially loved listening to on the Q701 and why.
(All of the below were Flac/MP3 sources, both 24/96 and 16/44.1 and where mp3, v0).
Soley - Pretty Face
The piano keys pop in and out with each stroke and are perfectly suited to the soundstage of these headphones. Her vocals chime in wide and everything has a nice sense of space to it.
Muddy Waters - Mannish Boy
Blues music sounds amazing on the Q701 and old Muddy's track is no exception. Supporting instruments dominate the right side of my head while his voice the centre and main instrumentation the left and they all come together for something quite special. The X1 does this track really well but the signature of the Q701 just finishes it off nicer.
Lana Del ray - Video Games
Lana's voice is amazing on any headphone but it owns the whole range on this track on the Q701..
Joan As Police Woman - Run For Love
This song is a good example of vocals being more centralised in the soundstage compared to the X1 which likes to widen them out a bit more (which suits the signature of the X1). The instruments are all around the vocals on the Q701 here though and it works really well. It feels like surround sound, like as if you're in a dream and supporting vocals are all around you with the lead directly in the middle.
Hugh Laurie - The St. Louis Blues
Vocals don't start in this track until around 2m40s in but before that you're treated to a wonderful presentation building up to them. A great track to get a good feel for the Q701.
Freeway & Jake One - Money
I listen to a lot of hip-hop/r&b and the Stimulus Package is one of my more recent favourites. This track has a nice blend of instruments and background vocals which come and go throughout. Main vocals again are centrally focused. At first I didn't know what to think but once the other stuff starts to come in it makes sense. I prefer the bass of the X1 for Hip-Hop but I respect the overall sound more coming from the Q701 for it. It just has a bit more intimacy.
Bonnie Raitt - Used to Rule the World
The electronic instruments supporting Bonnie surround your head. Much like above with Run For Love.
Daft Punk - Lose Yourself To Dance
This track has a very bassy rhythm which the X1 loved and I loved listening to as well. The Q701 doesn't quite reproduce that same bass detail but it's tight and present. It makes up for it, you guessed it, in the mids and the soundstage comes into it's own. I miss the bass in this track but not enough given the advantages elsewhere in the sound.
Notorious BIG - I Got A Story To Tell
Similar to Freeway's track but on this one we have fewer instruments.
Childish Gambino - Heartbeat
On the flipside I found this track to feel slightly fatiguing on the Q701. The beat is different to most other tracks in my collection. Fast paced and more dance than Hip-Hip I guess. The X1 works better for this track because of the repeated bass rhythm. Very detailed still but just not suited to the Q701 to my ears anyway.
So that's the first couple of hours of listening. I've not noticed any difference in "grain" as some people have mentioned grain on the X1 on various forums.
For £212 as they are now on Amazon the sound quality represents that price nicely I would say. Certainly not though for build quality. I feel as though if I dropped my X1 then they would not crack or break whereas I'd be scared of dropping the Q701. I'm sure they will be fine of course but first impressions count for something surely. At £95 though with the Massdrop group buy they're an absolute bargain. Considering I paid £150 for the X1.
I'll be selling the X1 soon and I'm sure I can get the bulk of that cost back. It's been nice having the X1 for the few months so far but they've met their match for my personal preference anyway in terms of sound quality. Their new owner will definitely enjoy them.
Regarding the source I plugged them in to, I have a NAD D 3020 via my PC connected by USB. The headphones out is perfectly capable of driving the Q701. I needed to increase the volume slightly more than what I did for the X1 but not by much. In relation to this the HD598 would get the sale volume with a lower figure on the dial compared to both X1 and Q701.
So in short I can forgive the build quality and niggles because the sound is so good and at £95 I've saved over £100! If I upgrade in a year to 2 years then I'll make that money back without issue.