I think blind testing of large groups in unfamiliar locations with unfamiliar systems with unfamiliar songs played at pre-determined durations is utterly useless. That might be good enough to tell a Maggie apart from a B&W, but for two largely similar DACs? Forget it, you'll get 50/50.
Carried over from what mav said on the shoutbox, and I'm going to fill this out later, let's start with the biggest pet peeve. "Placebo" in general is a medical term to explain anomolous efficacy in sham medical treatments. It's not a pejorative term to be thrown about by audiophiles and it's not a disease suffered by tone deaf philistines.
Excellent post. I don't mean to attack anyone specifically, but the shouts of "placebo!!!" can be obnoxious, as can the claims that "most of the differences people claim to hear don't exist" or something to that effect. When it comes to something like a headphone, you can often point to a specific measurement result and say "this area is going to sound a certain way" which different people may react to differently. Some of us are more sensitive to aggressive treble response than others, for example. When you take two different products where the majority of measured differences are theoretically below the audible threshold, that's a different story, and in those cases I would wonder on what basis you can claim that someone else can or cannot claim to hear an acoustic phenomena.
Might depend on what you're trying to distinguish. I did a bit of 320kbps vs Flac testing at my friend's house with resolving enough gear (HD600 and an Asio configured interface, probably from E-mu). It was different parts of the same song, but it was clear every time to my ears. I think I did 10-15 listens, though with the possibility to repeat, and got each one right. Without the possibility to repeat, my concentration might not just be good enough to tell with one listen, regardless of what I'm trying to tell apart, exception probably being the two last components of a gear chain. But yes, "largely similar dacs" without familiarized gear is another story, I'll agree on that.
Tube amps and particularly SETs distort, and they distort differently than SS amps do. A very neutral sounding SS amp should be easy to tell apart from a very "tubey" SET. You can engineer a SS Class A amp to sound very tube like by purposefully not chasing the hyper low distortion of the conventional A/B amp. I'm of the opinion that chasing more zeros in your distortion figures actually leads to a worse sounding amp, or at least a more clinical one.
