Regarding first comment - thanks, i think i understand it, basically the impedence output of the pono suits headphones 40 and under.....but anything over 40 is not ideal because the potential for bass drop off (and of course lower volume). Ive actually never owned a special DAP, I always assumed they had a a nice amp built in, why else use one?
Regarding size - well, i am someone that likes to go as light as possible, carrying an extra amp for my phone, perhaps, but not a phone, player, and amp. Its too many devices for me, I would be annoyed trying to charge them all. Of course to get the best sound I know you need to do things. I would love to hear a setup like that! As for headphone size, I am interested in using phones like the OK1 or PK1 so they dont take up a lot of space.
NO....the impedance output of PONO suits headphones with AT LEAST 40 OHM IMPEDANCE, that means headphones of 40 OHM AND HIGHER are needed. The rule of thumb is the output impedance number of a player times eight. 5 x 8 = 40. 40 is the optimal LOWEST number but 30 will do almost as well. Headphones with impedances below 30 would start showing audio signal distortions and lower signal to noise ratio [the "distance" or level between clean signal and unwanted electronic noise / hum drops and this means the 'noise' gets louder relative to sound of music]. The impedances mismatching also leads to power waste turned into increased heat which is not good for the electronics. On low quality headphones mild impedances mismatch would not show itself as lowered quality of sound. With good headphones the more serious impedances mismatch would show itself in the lowered quality of sound as the number gets below 4 - in this case that means the number of PONO's impedance, 5, times 4 equals 20. Below 20 Ohm the number would be less than 4 ....let's say 15 [Ohm headphones] divided by 5 [Ohm player] equals 3. So 'damping factor' 3 is too low [15 Ohm is too low], the number should be at least 4 [20 Ohm] and optimally for best efficiency it should be 8 [40 Ohm].
PONO is safe for almost all headphones, there are almost none with impedances below 30 or 20.
When headphones are plugged in straight to a player then the bass drop-off increases as the impedance numbers of headphones increase, progressively more voltage is required to move headphones' driver so that it can properly reproduce bass frequencies. The problem is portable players do not have electronic components required to produce bigger voltages needed to overcome the higher impedances. These components are more bulky and cost more, no portable player is big enough to accommodate their size plus there is a problem of manufacturers trying to produce things on the cheap, to maximize the profits. They use as cheap and as low quality components as possible.
To drive headphones with a nominal number of 600 Ohm a voltage of some 30 Volts is required and no portable player on this Earth is capable of providing it. 'The Continental' amp uses tube / valve in a pre-amp set-up within this amplifier to create sufficient voltage gain / number to amplify the audio signal to overcome the 600 + Ohm impedance. In crude layman's terms think of it as a problem of having to overcome an 'impeding' force. A bigger counter push / force is required to send the electric current through and this bigger push / force is bigger voltage. So the bigger the Ohm number the bigger voltage is required. I said 600 + Ohm because the impedances numbers of headphones are nominal. In the case of Bayerdynamic T1 600 Ohm is the number given but this number does not uniformly reflect 'the impedance curve' which is a composite. This curve shows that the headphones' driver is a varied 'impeding' object, that its impedance number changes depending on what part of sound it has to reproduce. It is hardest to force it to move to reproduce bass sound waves.
Here is the impedance curve of Beyerdynamic T1 [thanks to en.goldenears.net ]
- http://en.goldenears.net/16822
The impedance of the T1's driver when it has to reproduce bass [centered on 100 Hz ] is actually around 1250 Ohm which is a lot. T1, when plugged straight to an under powered player, will have an anemic weak bass. An amplifier is needed for these headphones to provide big voltage swing to move the driver to reproduce bass frequencies in strength.
So if a manufacturer says : "This player can drive 600 Ohm headphones", it most probably is not true. From 600 Hz up to 20 000 Hz there would be no problem but from around 600 Hz down to 30 or 20 Hz a player would have to deal with 1250 Ohm impedance, twice the nominal number of 600 Ohm.
Similar case is with headphones that are nominally of 250 Ohm impedance. Below is the impedance curve of 250 Ohm Beyerdynamic DT 880.
These headphones' 'bass impedance', centered on 80 Hz, is not 250 Ohm but around 315 Ohm. If a portable player just manages to drive 250 Ohm headphones, if it just manages to deal with 250 Ohm impedance, then it means it actually can not drive them and thus it means that an amplifier is needed.
Many people complain that their higher impedance headphones, when played straight out of the headphones jack of portable players, have weak bass. Well, they should use a portable amplifier to hear better bass.
