I'll add my voice to the many who say these are a freaking bargain. I bought them over cans costing two or three times as much, and have no regrets. I say this as someone who also owns Audeze LCD3's. I don't want to take those with me when I travel, so these are my travel pair, and while they obviously aren't in the same league, I'm still happy to listen to them.
 
After comparing options, I bought them from Amazon for $120 with free shipping. I typically use them with a Fiio E17, which greatly improves the sound quality when listening from my Macbook Pro--without it, I don't really find the music enjoyable, even though people say these don't need a headphone amp.
 
I listen primarily to classical, vocalists, some jazz and other acoustic music.
 
The pressure is still fairly high on my head. Fortunately, they go around the ears, so it is not the ears that get the pressure, but the sides of my head. Still, I tend to take them off every hour or so to relax before resuming listening. It may be that over time they will loosen their grip a bit--I don't use them all that often.
 
My rating is based on their price; obviously there are much better cans if price is no object.

I purchased this from Todd the Vinyl Junkie along with a pair of Audeze LCD-3's. I had already decided to buy the Audeze's, and the Peak/Volcano was the #1 choice on this forum, and Todd offers a great return policy, so I felt confident in my purchase. I was more than satisfied with the result.
 
My source material comes  from my Macbook Pro running Audirvana Plus, feeding into one of two devices I have with high-end DACs. One of those devices is an OPPO BDP 105 that has been upgraded by The Upgrade Company in Michigan. This is a fantastic sounding player with its own headphone jack, but the sound quality was definitely better feeding the analog out from that device into the Peak/Volcano than using the Oppo directly.
 
As chance would have it, I needed to sell the preamp from my main system. That preamp was a Mark Levinson No. 32, which sells for about 7 times the cost of the Peak / Volcano. However, any port in a storm. I had ordered an integrated amp, but it took many months to arrive, and so I used the Peak / Volcano as my primary preamp for those months, in a system in which the wires were more expensive than that preamp. While I won't pretend that it was as good as the No. 32, it did remarkably well--really, outstanding for its price. It includes three single-ended inputs and single ended line out connecters. There's no remote control--just a volume knob, a standby knob, and an input selector--but I was amazed at how well it did. Compared with the far more expensive gear I was used to, its primary drawback was just a bit of emphasis on the upper bass--a feature that many users will probably appreciate (I tend to go for absolute neutrality).
 
I have only listed to it with the supplied Sophia Electric 6SN7 tube, although I have enjoyed reading the forums talking about tube rolling. During thie past 6 months, it has been totally reliable and consistent.
 
Back to its use as a headphone amp: I can't claim a fully accurate comparison, but it has sounded better than any of the headphone amps I have listened to in stores. Given that its sound quality as a system preamp matches that of preamps costing twice its price (although typically with better cosmetics and remotes), I would recommend it wholeheartedly. Adding to that is my appreciation for Todd and his very helpful policies, which take the risk out of auditioning it.