Originally Posted by sloowhand
So based on all of this, I'm guessing that the G1217 would be the better way to go since I will be driving K172 Pros (62 Ohms/105 dB) and Meze 99 Classics (32Ohms/103 dB), both of which are pretty easy to drive.
Not that I think the G1217 can't pull that off but you need to hold off a bit on the "easy to drive" label on the K712. Note that there are two figures used for that - sensitivity and efficiency - and while both can be used they aren't the exact same thing. In many cases manufacturers use them interchangeably, using one label and using the other figure which is numerically higher. You don't get to see the full specs on the websites for example.
Here's an example from Audiobot 9000 using the Asgard on the HD600 (97.5dB) and K712 (92.9dB). Equations are logarithmic and not linear, but if the K712 is supposedly rated at 105dB and that was comparable to the 97dB used by Sennheiser on the HD600 product page, and with the K712 getting a heck of a lot more power, the discrepancy in output should be more than 1dB. At first I'd think they just messed up the numbers, but then I remember seeing the K701 having 101dB on the AKG website (but in other sites it's listed at 93dB, closer to what audiobot9000 has in the database).
Asgard puts 380mW into HD600, gets max SPL of 123dB
Asgard puts roughly a litle under 1000mW, gets max SPL of 122dB
Basically, I'm saying Harman might have someone here reading the AKG threads and swapped out the figures at some point, which did lead to some threads having people quoting the 100dB+ figure and people thinking they should basically work like Grados. Unfortunately, that isn't the case. Again, this has more to do with clarification rather than the particular amp in question (the G1217).
Originally Posted by sloowhand
The Mk II appealed to me because it was an all tube design. I already have a Schiit Magni 2U which is kind of the opposite of "tube-y", very clear and true. An all tube design, I thought, would be what I was looking for as a counterpoint to that. Most of what I had read about hybrids is that they generally sound a lot more like fully solid state amps than fully tube amps. Would this not be the case with the Ember?
As much as there is a stereotype of what "tube" sound is, that kind of sound isn't necessarily just what tubes are limited to, and conversely, neither are solid state amps. This kind of sound is more associated with certain circuit types, like triodes (vs ultralinear) and for headphone amps, output transformerless amps. Make a proper single ended push pull amp with nothing in the circuit to distort and color the sound, and it can drive even a low impedance AKG properly. Heck, even the Valhalla doesn't warm up the sound as much as other OTL amps, it just in a way rounds out the sharpest bits of the treble, but if the peak is there on the headphone response or on the recording, it won't obliterate it.
On the upside, amps that have a gentle blunting effect than total warmification won't be applying that excessively to parts that don't need blunting. Case in point: my HD600 with worn out pads*on the Little Dot MkII made Norah Jones sound like she needed to snort spicy chicken soup to clear her sinuses. It's like the HD600 went to Veiledsoundistan or Soundedarkabia, was put on videos, got shamed, probably lashed, developed Stockholm Syndrome, and then came back totally covered up because that's what a headphone should be like to the ears of the true believer in warm sound.
Similarly, hybrids aren't necessarily always closer to solid state. Maybe some distortion (or lack thereof) characteristics are more similar, in that the output stage would have more power at 32ohms than at 300ohms (the opposite of an OTL amplifier) and if the output impedance was low then it won't drastically have more distortion on a K702 vs an HD600, but the circuit can still be tuned to have a certain sound if the engineer wanted it that way.
At the same time it might not necessarily be what the engineer wanted, but what the user can do with it considering tube rolling is far easier to do than op-amp rolling (something that AFAIK you can't just do on discrete components either). So while some might roll tubes to prevent the blocked sinus tendency of the LD MkII and bring it a bit closer to the Valhalla, you can probably get a hybrid amp to get closer to the blocked sinus effect if you get the right tube. You'll need to read up on what the amp generally sounds like and what tube rollers got out of each replacement tube type. Just note that it isn't just the general tube type that can affect the sound but also the brand of the tube. Some differences in specs can have different effects on each circuit, but generally if we're talking preamp tubes, it will mostly be consistent that whatever tube is known to be warmer or brighter will generally remain so on whatever amp they're used on.
And again the advantage in this scenario is that the Ember will require only one tube, making it easier to track changes if you have to go through several to figure out the sound you like, rather than have to try preamp and driver tubes (and a pair of each too, so when you buy tubes, you have to match the measurements on each pair).
*note that I wore out the new pads and used it on a Meier amp without the sound getting like that