"Son of Zen" is a different amp than Zen (article here). Pass calls it "balanced single-ended."

Nice design; it reminds me of the Son of Zen. If you haven't already, you could improve distortion a bit by matching the output transistors for hFE.

I had to double check, but take a look at loop_'s σ22 on the β22 gallery page for the layout of the Hammond case. It's a tight fit, but it does work.

My best was Mutemath at the Middle East Downstairs in Cambridge, MA. They are a truly fantastic band to see live; the drummer, Darren King, duct-tapes his monitor headphones to his head because he moves around so much, and the lead singer, Paul Meany, treats stages like a kid treats a jungle...

Do you have balanced headphones? If so, which ones?   I have a pair of Audio-Technica W5000 drivers in a donor pair of Beyerdynamic DT770's that I've setup as balanced.   If not, are you looking at balanced headphones or a balanced amp in the future?   I'm in the process of building...

Quote: I'll defer you to the prevailing wisdom on answering hard questions about magnets.

I've been looking at Shapeways because they can (allegedly) get 0.1mm tolerances with some materials. I also don't have access to any FDM prototyping facilities. I wouldn't trust either with creating threads though; I've been leaving spaces to add nuts flush with the parts to work around that...

Some thoughts/responses to questions; I've been going through a similar exercise, although electrostatic and out of plastic: For the SFI ribbon tweeters, you should try posting/reading the Orthodynamic Roundup thread. There's a very chance some of the regulars that post there will know of...

The Dynalo isn't an outdated design; the Dynahi and the DynaFET are two much larger, harder to build amps, where the transistors have had availability issues for a few years. The Dynahi and the DynaFET certainly outclass the Dynalo, but that doesn't mean it's obsolete.   With Grado's, I...

I can't speak to their quality, but the seller DIY-Goods has some chassis for sale, like http://cgi.ebay.com/Aluminum-int-pre-amplifier-Chassis-Case-Audio-DIY-A-28-/230538948440?pt=LH_DefaultDomain_0&hash=item35ad312f58. VT4C has some as well, as does thlaudio. In the aforementioned cases...

Things I never thought I'd say in the Sponsor Annoucements forum:   ygpm

  Quote: I'd suggest doing just that. I didn't, and I find myself missing a power switch a lot. You only blow a fuse once or twice (hopefully ) and switch the power switch every time you use the amp. It would probably beat plugging/unplugging the transformer or the fuse. In the...

You should probably make posts like this in the DIY forum. This in particular could comfortably fit in the DIY Cable Gallery!! thread.

Build it and then make a matching set of stone speakers (DIY Granite Speakers) .   I read a while ago about ceramic computer cases by "Plush Department Design Company" (linky). Seems like they make an amplifier too?   Give it a try. There are some very sturdy ceramic glazes, so I doubt...

Quote: They're both Switchcraft, so I doubt you'd notice a difference between them for audio quality. I might suggest the second one unless you want to be able to attach a guitar strap to your headphone amp .