I just posted this in another thread that I had started a few days ago, which was asking if the Q701 would sound similar enough to the GR01 or the rest of the TWFK BA based IEM's. I was looking for an answer from somebody who has used both, nobody really answered, but now that I have them I can answer, and the answer is yes. I figured this information may be useful here as well.
These Q701 sound similar in overall tone, overall frequency response. They are neutral, and extended on both ends. They seem like an exact, but obviously full size (over ear) copy of a GR01. I am using the +2db bass boost on my Fiio E17 though, so they would have a tiny bit less bass otherwise. Who knows, maybe after break in I will no longer feel the need to use the +2db bass boost. We will have to wait and see if i notice anymore change in the sound. They actually already sound cleaner than they did when I first put them on. At first they sounded kind of tight and congested, but after a few minutes that went away.
These actually seem to have even better detail retrieval than my GR01 has, but I must include that I have never plugged the GR01 into anything other than my iPhone 4 headphone jack, so they may also sound better out of the E17. Anyway, not to sound cliche, but I am noticing details I have never heard before in music, even when compared to the already highly detailed GR01. It's tough to say what the best part of these headphones is, but I am immediately impressed with the texture and details in the bottom end. The detail, texture, and impact in the bass is great. Sure, a basshead will find these bass light, but for what they are and the music I will use them for, they are still punchy and have plenty of bass quantity(with the +2db boost). Drums in rock and metal, and even jazzy rock music, sound very dynamic on these too, best dynamics I have ever heard from a headphone. Crank them up a bit and the mids are actually quite fun. Treble is of course plentiful, extended and detailed. Some may say bright, but I so far dont find them harsh or sibilant. They are revealing of bad source material though, so a clipped or sibilant recording is going to sound clipped and sibilant.
Off topic, but I have to admit how drastically my tastes have changed. About a year ago I had the HD650 on a full size HeadRoom desktop amp/dac (about a $1200 setup). Back then I would have found the Q701 to be bass light, and harsh, but now this is the signature I like. At some point I realized that my musical tastes called for a sound that is less bassy and less warm. I have turned into a detail junkie.
I am also happy to report that these sound great from just an E17. Some people had me worried that a smallish portable amp would not suffice, but there is plenty of power and headroom here. These to me, arent a headphone that was designed to be listened to at extreme volume anyway. The Q701 will get tiring at high volumes anyway, so why use an amp that is waaay overkill in the power department. With my iPhone 4 as the source using a Fiio L3 LOD with the E17 on high gain (12db) I am still under 30 out of 60 on the volume control most of the time. I am actually listening at an average of about 25 (out of 60) on the volume control. For example 25 of 60 while listening to a song called Divinity by a band called Threshold is playing at about 82-85db measured with a Radio Shack spl meter. Low to mid 80's is usually where i like to listen. It may be a tad loud, but still safe for long periods. Some may say I am still not hearing these to their full potential, but who is to say what their full potential may be. Maybe my amp is only driving them to 95% of their full potential, but I am quite impressed with what I am hearing and can definitely say that an E17 is plenty for these.
At the price of this setup, it seems like a steal. I got the Q701 for $240, and the E17 for $140, both brand new in sealed packages. So for $380 it's a great setup. Of course my source, the 32 gb iPhone 4 costs a bit of money too, but I already had that. I also have a laptop that I can use with this setup, but so far I have only plugged the E17 into my iPhone. I will try it with my laptop eventually.
Also, I have not noticed any EMI from my CDMA iPhone messing with the E17 yet, and I Have it sitting right next to it, less than an inch away. Meanwhile the lesser E5 would be just about unusable with my iPhone without putting it in airplane mode.
So, to sum up, if you have a TWFK based IEM and want a full size that sounds pretty much identical, the Q701 may be your best bet. Or if you already have a Q701 and want the same sound in an IEM, then the GR01 or another TWFK based IEM may be the way to go.