You guys may also want to try the Samson R600. Sam Ash here has them on a listening display. Similarly good audio quality, but it's less deep, less bassy, and much faster/more energetic. The pads aren't as good either. I got it because it doesn't leak as much sound as the 850. So far I just use them straight into my tablet's headphone out with no EQ. Wish I could get them a little louder. AKG 240 Studio was only $60 with free shipping last I saw on amazon. That one is a little more refined, but you definitely need an amp and it also is a bit muddier. Even when I plugged the 240 into the setup I use with my K701(Arcam 73/Heed Canamp), the sound would sort of fall apart when things got too bassy in a song just like when I used them in the tablet. The bass would just overwhelm things. So far I haven't seen much of a point in using the Samson headphones in my home setup when I have a K701. I think the Samson stuff competes with it pretty well. I'd take these Samsons over my Grado stuff, including the RS-1. I should compare them to my 600 ohm DT990 sometime, but I never use that phone. I like the Samson stuff better than a lot of what I've heard at stores and Can Jam, including stuff like the HD800, PS-1, HD650, LCD2, various Denons, AKG 550, and quite a few others. Last I saw on amazon, the Superlux 668 was $32. I probably use the 850 more than the 701 now since I can bring it with me wherever. The 701 definitely has a bit more refinement and a decently bigger soundstage, but I don't miss it a ton when I'm using the 850s. I think the bass could be toned down some, so if the 668 is not as bassy, I may like that better. The 850 and 240 both provide about the same top-notch vocal reproduction that you find in the 701. You get the same big, immersive sound that surrounds you when overdubbed vocals are used like on Bonnie Tyler's Secret Dreams album. Instrument separation is also pretty good with these, falling just shy of the 701. I don't find the 850s to be shrill at all. In fact, they are quite warm no matter what I plug them into.
It's really remarkable that something this cheap can provide such a value. If you don't want to spend thousands buying and fiddling with all sorts of different gear, seems you can have a very good headphone experience with this Samson and Superlux stuff. I plan to get whatever DAP I read about on here that had the same Wolfson dac as my Arcam and line out, plus one of these Fiio amps. Both those items were under $100 each last I checked. As time goes on, I expect to see even more top notch stuff at low prices.
