Originally Posted by swannie007
I happen to own both of these cans and prefer the 681 Evo's for comfort and sound.
Originally Posted by PurpleAngel
I would say to give the HD681 EVOs a shot.
I ended up getting the HD681 EVO's. I tried them stock for a few days and compared them to the A700x's (it's the only cans I had around to do a side by side comparison, but i have heard many cans before). After some break in, I made some of the modifications mentioned by Solderdude in a PDF. After even more break in, I compared it to the A700x's once more and listened to several differences:
Definitely way more bass in the HD681 EVOs than the AT's. Bass was more boomy at first but after some mods and break in (velour, felt removal, covering up some vents, no filter), bass sounded a bit more controlled and punchy. If you want very controlled bass then install a filter.
Mids and highs
Definitely there is a lot to talk about here. From what I discovered, there are two versions of the HD681 EVO's. The newer version comes with additional velour pads and a lot of little factory improvements (better rubber band, different vent covering material, etc.), the old version doesn't. The mids and highs vary between these two as well, mostly around the 5k range where there was a significant -db drop in the older version that has been since improved. The stock HD681 EVOs initially sounded a bit muddled, but after some break in, plus the mods, the sound became way more comparable to the ATs. The ATs still have the edge in sound quality and clarity, but for the price difference, I was absolutely impressed on what the EVO's were presenting to my ears. Besides, many EVO users have reported that these cans get even better after 100-150 hours of break in, so kudos to that.
The original A700s, although i have never tried them, are widely known to have some of the best and widest sound-stage for the money. I have the A700xs and I was blown away when I first heard them. I listened to 3D audio, surround sound videos and games while making my comparisons with the EVO's. The A700xs still have the upper hand by a slight margin, but the EVO's did not disappoint at all and are just behind. There is roughly a 15-25% difference in the sound-stage clarity, but i believe that has to do with the superiority in the AT's mids and highs clarity. However, i believe that in terms of sound-stage depth, there is a significantly smaller margin of about 5-10%, although it felt like the EVOs had a more defined circular stage (more on that below). In regards to pinpoint accuracy, i believe this is very subjective with in recording quality, the amp you use, the type of surround sound technology, your mind and how spatially conscious you are, the modifications you have made to the EVO's, and many more factors. I was able to accurately position sound cues on both cans very well. Both cans have a different way of executing it. The A700xs are good at orientating me when things are to the side or behind, but drowned a bit when things are in front or above, whereas the EVO's seemed to have a slight better circumnaural accuracy. Regardless of which cans you use, accuracy gets VERY confusing when there are a lot of cues at once.
After 40-50 hours so far i can say that these cans have exceeded my expectations, and they only cost me $37 dollars versus $135. They are definitely comfortable and are getting better by the day. Go Superlux. I ended up returning my A700xs, period.
Hope this helps and reply if you have more specific questions.