How much power is needed depends on the efficiency in dBmW.
So it depends whether you are driving a 75dB/mW headphone or 115dB/mW
Then there is the issue that some people think they need lots of power.
In case of the T90's these are 400 Ohm and 101dB/V yet somewhat efficient as they are 97dB/mW
In case of the HE560 these are 45 Ohm and 99dB/V yet somewhat inefficient as they are 86dB/mW
So at the same volume level they sound about equally loud yet the HE560 requires 10x more power.
To reach impressive levels you need to reach 120dB SPL peaks.
8.9V for the T90's and 11V for the HE560.
0.2W for the T90's and 2.7W for the HE560
That's quite some spread and it is very obvious you really don't need 0.7W for T90's (125dB) but you will need 2.8W for the HE560.
The poll is going to draw opinions based on belief people have rather than give any insight in what people actually need.
As 110dB peak is already sufficient for very loud listening levels which you cannot sustain for longer than 1 average song length your power requirements would drop rapidly.
2.8V for the T90's and 3.5V for the HE560.
0.02W for the T90's and 0.3W for the HE560.
T90 are 250 ohm BTW, unless they revised them at some point. https://north-america.beyerdynamic.com/catalog/product/view/_ignore_category/1/id/3033/s/t-90/How much power is needed depends on the efficiency in dBmW.
So it depends whether you are driving a 75dB/mW headphone or 115dB/mW
Then there is the issue that some people think they need lots of power.
In case of the T90's these are 400 Ohm and 101dB/V yet somewhat efficient as they are 97dB/mW
In case of the HE560 these are 45 Ohm and 99dB/V yet somewhat inefficient as they are 86dB/mW
So at the same volume level they sound about equally loud yet the HE560 requires 10x more power.
To reach impressive levels you need to reach 120dB SPL peaks which one can only listen to for 30 seconds before the uncontrollable urge to turn down the volume takes over.
8.9V for the T90's and 11V for the HE560.
0.2W for the T90's and 2.7W for the HE560
That's quite some spread and it is very obvious you really don't need 0.7W for T90's (125dB) but you will need 2.8W for the HE560.
The poll is going to draw opinions based on belief people have rather than give any insight in what people actually need.
As 110dB peak is already sufficient for very loud listening levels which you cannot sustain for longer than 1 average song length your power requirements would drop rapidly.
2.8V for the T90's and 3.5V for the HE560.
20mW for the T90's and 300mW for the HE560.
That's quite some spread and it is very obvious you really don't need 0.7W for T90's (125dB) but you will need 2.8W for the HE560.
I do need that much for some blu ray and games, also the T90 are 250ohm. For example, I use 75-85% max power on the Gustard H10 (1.4w into 300ohm max) with the T90's with +12 gain/max power on.
I wonder if your audio sources had low output voltage, in which case the limitation you were running into was the voltage gain of the headphone amp, not its max output capability.
Oh, I've met people who listen that loud (or nearly that loud). I know how loud that is, sitting right in front of the trumpet section during band practice. (I wear 25 dB musician's earplugs when in that situation). Or a loud rock concert can get close to that. Some people consider that to be "live level" and listen to their music that way. And they do have impaired hearing.... You cannot possibly have used 1W in the T1 and actually listened to it. That would be 127dB SPL peak. ...
Well apparently this is with full 4v xlr inputs from dacs . So unless some massive drop in volume on the stereo downmix of blu ray, then OP may just need new ears.Oh, I've met people who listen that loud (or nearly that loud). I know how loud that is, sitting right in front of the trumpet section during band practice. (I wear 25 dB musician's earplugs when in that situation). Or a loud rock concert can get close to that. Some people consider that to be "live level" and listen to their music that way. And they do have impaired hearing.
However, I'm not necessarily saying the OP is one of them. Maybe he is, or maybe he just ran out of voltage gain from low level sources, and mistakenly thought the "amp wasn't powerful enough".