I'm using the Audiophilleo2 with the optional PurePower battery mod. The combo together is about a grand, but is amazing and finally takes the computer out of the equation (the PurePower was much bigger improvement than I expected). That would have seemed crazy to me a couple of years ago when I was newer in the hobby, but all of my listening experience has made me value a couple of things really highly like quality of power, and the interface when using a computer as a transport (while there are many good and affordable solutions, I haven't found anything less expensive than AP2/PP that truly approaches a high-end player and takes the computer out of the equation). I sold the Sigma 11 to you at the same price I paid for it, so together the HDP Sigma 11 was well under the 1k mark.
The Woo Audio WA22 is a lovely amp and I really enjoy it. I love how sensitive it is to rolling tubes, which really lets you nail down synergy depending on your chain. I still use my HD 650 because of how amazing it has continued to scale with my current gear, especially with silver cabling (Moon Audio Silver Dragon XLR interconncts and balanced headphone cable). I have heard most of the flagship cans on my Woo and I think it does very well with most of the 300 ohm and higher cans like HD 650/ HD 800 / T1 etc. That being said, I personally don't feel it handles orthos very well - at least based on HE-5LE, and to a lesser extend LCD 2 rev1. HE-500 is rumored to do much better with it, but I haven't tried it yet.
Eddie Current amps are exceptional products. We've have Craig Uthus attend the last couple of larger meets we have had in the Phoenix area over the last few years. On both occasions he brought several of his flagship amps including the ZDT and Zana Deux. A local head-fi'er has the balancing act with HD 800 and it is phenominal. I would clearly place it a full step above my WA22.
Honestly, I could see adding HDP/Sigma 11 again as an office computer setup. It's amazing bang for the buck. I especially like the level of mico-detail it could resolve with the Sigma11.
Originally Posted by HeadphoneAddict
I had a prototype Woo WA22 here in the summer of 2009, and compared it to my new Eddie Current ZDT amp. The WA22 was very good with HD600 and HD800 and almost as good as the ZDT, although the ZDT had much better driving power for the low impedance Denon D7000. I imagine that the final production WA22 was better than the Prototype. I'm happy to add the DAC-100 to my list of "good with HD800" amps.
The DAC-100 is a step above the HDP, even when using the Sigma 11 PSU that takes the HDP up a notch, but it's no ZDT or WA22. On the other hand, when you get a DAC/amp that works this well with HD800 for this price, you don't want to let go of it. Although I'm using the DAC-100 instead of the HDP these days, I don't think I'll ever sell the HDP with S11 because it's such a great bang for the buck.
PS: What kind of USB > S/PDIF converter are you using that's so costly?