Informative as always obobskivich! I'll take it in a few pieces:
It's enough to damage your hearing PDQ. Dolby specifies peaks (note PEAKS) should be around 105 dB on the topside, assuming 85 dB is your "average" - I think that's too high for all day use, so I'd knock another 10 dB off the top. Anyone who wants to listen to triple digit SPLs is nuts.
Of course it causes hearing damage! :) I doubt I even listen near 85dB most of the time. I try to keep things at the same volume I'd hear it live and unamplified. Which is typically not loud for most of my music. Orchestra can be, though sometimes I think HE-400 has a little TOO much DR available for the sound of a live orchestra at normal seating positions.
My point was when you run the calculations of how loud an amp can drive something and come up with the peak SPL, it always makes it sound like "amp x is too much because it would be too loud" as though it has no volume knob :)
No, not really.
If it's been designed in the last 3-4 years and has Audyssey, 0.0 dB actually floats relative to the calibration. If it's older than that (say, ~2000) 0 dB represents an uncalibrated reference level. If it's much older (say, 1995), 0 dB is probably full open, and generally there is no gain to be had beyond it. Digital gain is always nasty, but it only exists on digital preamps - on a conventional receiver/amplifier (like the Yamaha IA I have upstairs) you can run it all the way up to 11 with no problems.
You're probably right about Audyssey, but I do remember some info (perhaps inaccurate info) from years ago that reported that driving over 0.0dB was either applying digital gain or overdriving the poweramp. May by the old Onkyo piece that died a long time ago actually, I think it was in the manual. It was definitively recommended to keep it at no more than 70% to prevent clipping and distortion. Could have been poor design. It wasn't the most expensive piece
Perhaps its old audiophile myth, or perhaps its related to older gear, about keeping the knob between 11:00 and 1:00 as the sweet spot and not buying something too big or too small to keep it in that zone.
All the way up to 11....
No, not really. The signal and load are what determine this. For example if I feed a signal at -50 dB into an IA and run it up to 10, it doesn't matter - it won't clip. I can also push it into clipping with the volume on the lowest setting by driving the input stage too hot. Distortion rises as power output increases, which is determined by the load relative to the output voltage (which is what you're controlling with the volume dial).
Isn't that related to the "sweet spot" issues for the dial?
Variables such as what? Yes, you could absolutely blow the transducers up with this amplifier - I'm not aware of any headphone that can take a ~10W input and live to tell about it.
The HE-Adapter is not a capacitor, at least not if I'm understanding their publications correctly. There is no "safety cap" that you could use here either - it's a series of resistors (you can build the thing yourself in an afternoon) to drop voltage and current. If you want to protect the cans you'd want PPTCs and fuses among other things - a really cheap (and very effective) implementation of this is used by Bose for their speakers, and I believe it was originally sourced from Tyco (who makes said PPTCs), involving an automotive lightbulb and a reasonably high value PPTC. It protects the tweeters (which have the least power handling) from overloading - that's what the "active speaker protection" they talk about is. I'm not aware of anyone else who does this though; shame. They're inefficient inasmuch as they're loading a higher resistance, but it's all dictated by Ohm's Law. I'm not sure what magical hidden variables you're worrying about - are we to believe that you disagree with all published specs, measurements, Ohm's Law, etc in relation to this set-up? Or what? (I'm confused).
Me neither. My point about variables was if there's something else about HE-6 or about the interaction of a 53ohm load on an amplifier designed to drive an 8ohm load that means that the drivers aren't actually getting the 10W it would otherwise appear to? There are reports in that HE-6 amp thread of some vintage speaker amps that simply won't drive the 53ohm load at ALL, it just won't play. And since Fang seems to have no issues with crazy high power amps, and many users (subjective in the usual Head-Fi sense of course! Grain of salt required!) have reported great success with them, it makes me wonder if driving that kind of impedance causes any other inefficiencies in the amp (which would cause more power vented as heat as well...conservation of energy applies of course), meaning that the 45W @ 8ohm amp doesn't REALLY drive the 8-10W into 53ohms that ohms law would otherwise apply.
I'm not saying that is the case, I'm saying I would be curious to find out if anything like that is the case as it would explain why even higher powered amps are often apparently sought for HE6, and why Fang (who should know the drivers better than anyone) seems to have zero safety concerns below 50wpc to 70wpc depending on what day he talks about it, when wattages far lower than that, by the basics of ohms law should, on paper, blow the 8W capacity....unless it's not REALLY getting all of what ohms law suggests due to other factors. That's why I was wondering about maybe there's some variables missing that affect the equation beyond the basics. More of a theoretical curiosity. I wonder if Fang still responds to technical PMs? I know he was too busy a few months ago, but HE-300 & HE-400 were still ramping up back then. but it would be interesting to find out. The specs state 50 (Tyll says 53) ohms, and an 8W max load. Based on the basics of ohms law, that should mean, what, a 30wpc amp should be more than able to blow the drivers. Yet Fang says that below 50 (or 70) it won't. Either some factor we're not looking at is changing the numbers from the amps to lower watts than you'd think, or Fang got it wrong on the fly...always possible.
So the question is, 6W into what? And then how hot is your source, and what's Lyr's sensitivity? And then what's Znom of the load, and so on, and then you can figure out how much power it's actually giving up. Dollar says it's under 10 mW.
Actively, or at max? It can certainly push out more than 10mW at max, but your question is right, 6W into what, that I do not know. I would think into 8ohm, but if it's a little marketing (and Jason IS good at the marketing!) it could be 4ohm. It's a shiny, impressive number for a headphone amp that means little without knowing the impedance, and I never stopped to consider that. However I do know it can put out crazy power for a headphone amp, but apparently doesn't do well with HE-6 despite driving it loud. That is thankfully something I'll be able to do my own tests with in a week!
The source seems fairly not. I swear the Squeezebox locked at 100% must be applying digital gain still, and yet 100% is supposed to be the bit-perfect mode. But no other digital source I have pushes things as hot as the Squeezebox digital out does. It's feeding Bifrost, which should be 2vrms nominal. And it's not an anomaly, I have two Bifrosts. So it's a standard analog line level that seems to run extra hot when fed by the Squeezebox Touch. I've been curious about that for a while but can't find information to figure it out. If I plug another digital source into it, it's about HALF as hot as with the Touch. I also have two Touches...same deal on both. Either most other digital sources fudge the numbers and apply digital gain cut, or Logitech fudges the numbers and applies digital gain boost when it's not supposed to. In either ccase it does it in 24-bit space, so at least that's good. But it's still kind of unnerving.
I do wonder what the difference, sound wise, would be between a higher powered amp and not. If the power means anything or if it's just a higher qualitity piece of gear. Two things I like about 8004 is the power-direct so I could have fed Lyr's tubes into it as a pre (but I"m not sure I want to) and an extra tone control for mids that would have been nice, though most of the time I'd do source-direct and bypass the tone controls anyway. Other than that, I'd be curious if they'd sound identical despite the output difference or if one's just a better amp. I think the wattage difference is more important with lower impedance no matter what though...meaning real speakers.
And yeah, I've always liked Marantz. I was going to get a Marantz for my main HT AVR when I ended up with the Denon instead, but that particular Marantz model that year had SERIOUS known issues that they were almost guaranteed to fry themselves within two years.
I like Denon a lot, don't get me wrong, but they have a much colder, more analytical, more O2 like sound to them. Marantz tends to be smooth and warm if a little over-zealous on the midbass. I have to say though my Denon amp is a good match to my already very warm, mid-centric JBL speakers (drives me nuts when people smite JBL, some of their lines suck, true,but...Studio L is a heck of a bargain....mass-market pricing for a really nice speaker overall. It's the HD650 of the loudspeaker world (at its old pricing)....not the best thing on the planet, but for the money it's quite a performer, and scales wonderfully.)
What do you mean "not in current" - ??? Current is dictated by Ohm's Law and helps to figure power. It's not arbitrary or independent. The user gets to adjust voltage, the load gets to set Z (as impedance aka complex resistance), the source gets to set freq, and that will give you (through Ohm's Law) a given power demand which the amplifier has to be able to deliver as a combination of Vrms output and current delivery; if it can't do one or the other it has a problem. I'm not sure how to address the complaints over the "low end" - are these actually validated, or just subjective claims made after whomever purchased something shinier and more expensive and "compared" (in a non-controlled manner) the two? It's hard to say what's going on without more information.
We'll see. I'll certainly test it on both the Lyr and the Marantz. Both are known to drive it plenty loud, but Lyr is one of the mythical low-end lacking amps. So if it's all about loudness both should be balanced since both can drive it loud. I assume as a planar it has linear impedance. I won't be comparing against other big amps though, at least not for a while. My impression from just reading is that the complaints about low-end aren't mere subjective "hey the bass is tighter and deeper extension" type reports so much as "what's wrong with these things, they're bright and screechy" type issues. It sounds more like complaints that it's definitively shifted in the tonal balance than just complaints about impact. But I'll get to verify that for myself soon enough.
None of the above is meant to attack, just to inform (including you informing me, because I'm confused by some of your statements).
I've had enough discussions with you to know that while your approach may seem accusing, you don't intend it that way. Not everyone is familiar with your approach, but I know no offense is meant!