Quite a few less-than-polite replies here. You guys need to be better ambassadors to new members. It goes without saying that new members should search, and try to understand the layout of a new forum. When it doesn't happen, don't tell them what they should have done, or known.
The straight and true of it, Shaffer, is that your question, posed in the high end forum, was answered in the first reply, and within an hour of your posting. http://www.head-fi.org/t/682248/which-amplifiers-should-i-consider#post_9816208
For me, the GS-X + HD800 is the end of the road. This Summit-Fi forum is somewhat about price, but also about what people are satisfied with being their endgame solution. There are certainly people who have spent many times what I have on my rig, and are still searching for the end. Does this mean my 'summit' hasn't been reached, just because of a certain monetary value? Not at all.
It is difficult for me to go backwards to find amps at a cheaper price point with the goal of ultimate transparency, because it doesn't exist, at least not to the extent I've discovered at the price point I shopped. That said a few amps that surprised me were the: Objective 2, generally very clear and resolving, though lacking dynamics and can sound a little compressed because of it. This is an inexpensive item that punches well above it's weight. Next is the Matrix M-Stage, which tends to have synergies with surprising headphones, and can end up merely average with others. Another popular amplifier, which is designed to run highly resistive loads (though typically sensitivity, not impedance) is the Schiit Lyr, a hybrid amp, with many many pages worth of tube rolling knowledge to peruse. Something a step up, and fully tubed, the Little Dot MKVI+ is a balanced amplifier that works very well for high impedance headphones such as your 880, and many other popular models that are 300 or 600 ohm. The catch there is you would need to reterminate your headphones to balanced configuration, or, if your headphone has removable cables, get a custom cable made for it (usually easy to find for popular models). There are some higher power single ended amps that also offer exceptional sound quality, but most of those are well over 1000 and into summit-fi territory. This is just a small list to get you started. There are many many amps out there, and I haven't listened to even a significant portion of them, so I can't tell you what to get, not that I would anyway because my taste is likely different.
If you want to venture into electrostats, your budget needs to increase at least twice to get near a reference sound quality. Both the headphones and amps are very much small run items, so overhead plays a bigger role in the final price. The amps are actually fairly dangerous to work on if you don't know what you are doing, or are not careful. Many companies don't bother with the risk, so there is less competition, meaning prices have even more leverage to stay high. There are some less expensive ways to get into stats, but most of them are significantly colored in one way or another.
