IMHO (YMMV, pigs might fly etc) it's not about
power. With the LCD-3C there was some consensus it was a much more picky phone than the LCD-2. IDK, as I've never heard the C.
When I bought a 3F I thought at first all was good with my various amps. Not so. My tube amps needed a little tube-rolling - still getting there - and of my SS amps the only acceptable (and actually
good) one is the Meier Classic (rejected: BMC Puredac's balanced hp out; Violectric V100). The Lyr (1st version) was
not in the running with my mid-level tubes, most troubling being a slight over-smoothing of detail and some colorations. (To be fair, I didn't spend much time on this as my Decware amps are my preference by far).
What I think I've learned is get a neutral, transparent, detailed amp (or tube configuration) for Audez'e phones. Do
not go warm as this is picked up by the LCDs' bass/lower mids capability and projected too much into the mix.
And yep, I would say the 3F is a choosey beast.
Final thoughts: you cannot be seriously questioning whether the Lyr (4W at 50 ohms) has enough power can you?
But remembering the Lyr was designed for orthos and lower impedances, it
could be the 3F's higher impedance presents a slight problem. Take with grain of salt - I'm not an EE.
FWIW, my Decware Taboo - essentially a speaker amp - drives the LCD2 rev 1 to perfection but it's my output-transformerless Decware CSP2 (a preamp that doubles as a dynamic hp amp - think Beyerdynamic, Sennheiser etc) that's winning with the 3F...
Good luck with the pads. I still think there might be a defect with that particular pad.