@mrspeakers Little Dot mk3 SE is a hybrid not a pure tube, and Im pretty sure it has quite high impedance from what I remember, but it sounds good with low impedance HPs I plugged with it. All low impedance HPs I tried on it sounded better than from only Aune S6.
Aune has several older models that have very high output Z and as a result can't deliver enough power. Newer models like the X7S are well suited to planars.
I've not heard the LDMk3 myself, glad to hear it sounds good. Pretty sure the LDmk3 is actually an OTL design not a hybrid. When you see power fall as impedance drops that generally indicates the amp swings voltage more than current and is optimized for higher impedance headphones, though it can still work within the limits of high much current it can push. If you look at the Little Dot Mk3 power spec you see power falls with load;
350 mW @ 300/600 ohm
300 mW @ 120 ohm
100 mW @ 32 ohm
My guess will be that this can only put out about 40mW into A2, so it will probably sound great up to clipping, but clipping will be no more than 106dB. That's louder than I would ever play except a symphony crescendo, but I tend to listen at low levels to protect my ears. Just a caveat emptor for those interested in this particular amp. From these numbers the amp is optimized for 300ohm dynamics.
To find good matches in amps here are a few simple tricks:
1) All our headphones range from 12.5-27ohms. Try to find amps that rate power at 32 and/or 16ohms and look for at least 150mW at 16.
2) Be careful with OTL amps, they may work great like the LTA units, or they may just run out of gas at low volumes. Ask the maker how well it will handle low impedance loads.
3) For tubes amps check there's a Low impedance output switch or tap and if so that its 8-32 ohms for max power transfer. A big amp can have higher output impedance and still work fine.
4) For solid state amps try to get <2ohms output impedance. Over 10 ohms = lots of power lost to heat in the amp instead of to sound.
