Correct pads arrived at the end of last week! Thanks to HFM customer service for sending me the correct pads and letting me keep the old ones. Exterior dimensions are the same, but the 'correct' pads have a slightly bigger interior dimension. So the pad is about 2mm thinner all the way around. The depth seems to be about the same. And of course the 'correct' pads don't have the cloth dust cover. An interesting note - the newer pads look like they come off the factory line with more clips, half of which get cut off to equate to the same number of clips as the old style.
Sound wise - the lack of cloth results in more of the high frequencies to actually come through. Before acoustic instruments sounded slightly artificially muted. Especially pianos sounded unnaturally warm and tubby. Having more high frequencies balances that out to be more natural, though still warm leaning due to the flat response from 100hz-1khz, which tends to sound warmer than neutral IMO. (BTW, that opinion is founded by the fact I record acoustic performances for a living so I am very aware of what my recordings 'should' sound like). Soundstage wise is about the same, but imaging is different, I can't exactly say what is different.
Overall headphone impressions after two weeks - This is the most organic soundstage I have heard (havent auditioned any high end headphones). More so than the bigger soundstage, the imaging feels spot on. Instruments have good width to them. The recordings I have done strike a very good balance with separation and blend. Much more natural than my HD600's, which feel like the center of an instruments sound is strong, but with an uneven blend from the instruments center to the rest of the soundstage. The imaging is very lifelike, assuming the recording was captured well. The sense of depth is also really amazing. Though I actually find it more distracting than good, because it makes me realize the flaws of microphone placement more than I'd like.
FR is meh. It's almost natural, but like I said before there should be more upper mids than lower mids to my ears. A good example of this is a piano because the very low strings have a LOT of harmonics. The higher notes sound natural, but the lower harmonically rich strings dont come across as rich as they would in person. Of course EQ'ing the 1.5k dip helps, but I find I need to EQ 150-300hz as well by just a db or two. THEN the harmonic proportion feels really close to natural! I dont find the treble ever sibilant or harsh. Interestingly, the 1.5k dip has unpredictable effects on drum kits. Some kits really disappear in the dip, others are brought out by the 3-5k emphasis. The only time the treble ever feels off is in modern vocals. The usage of bright sounding vocal mics in a mix for presence can really come across as thin due to the 1.5k dip and then emphasis in the same areas these bright microphones are emphasizing (6-10kHz). It doesn't bother me that much because modern vocals aren't really recorded to prioritize naturalness in the first place.
Transients/Dynamics are disappointing across the entire frequency range. The presentation is soft and dynamics aren't reproduced in an exciting way. I don't feel excited by rhythmically complex guitars or drums because of the softer transients. Timpani's sound unnatural because there isnt enough transient. In general, the louder the transient is supposed to be, the less it's there. A quiet piano sounds fine, but the moments something grandiose is played, the attack of the hammer hitting the string doesnt feel right. It feels smoothed and unpercussive. This is not just slam from LF, this is across the board.
I really love how immersive the sound is. It's so addicting! But this is not a natural sounding headphone IMO. Perhaps those less familiar with how acoustic instruments sound like wont be so bothered by its inadequate properties. At least now I know I need to save up for an HD800, especially since I am not treble sensitive.