Here's my take on the HE-6 w/ LCD-3 pads:
Soundstage width really becomes larger. Instantly apparent. The left and right is larger than my HD800, it sounds very much like speakers. The depth and height also increases, but not as much. You really get much more airiness in the sound; it's nice, but does have drawbacks.
The bass becomes less visceral and loses some of its warmth/ seems to decay faster. The bass presence is basically diminished.
The highs become much crisper which, and to my ears, are much better in terms of accuracy/timbre/realism. However, they do get a bit crunchy so it can equally be a drawback. The timbre of cymbal splashes/crashes is unparalleled and better than how my HD800 would render them; yet so real is may be agressive. In contrast, with the velours, the HE-6 sometimes have a bit more of a graininess to the highs past 6khz; it seems as though they're not as refined. Some people sometimes complain about the weird little peaks in the HE-6's highs
(but it's hardly noticeable unless you try hard to find them or compare to HD800/LCD3), which to me are their only slight weakness. The LCD3 pads seem to correct timbre and natural decay of most high frequency notes but at the expense of the whole sounding more forward.
Basically, LCD3 pads on the HE-6 image much better
(which is incredible considering HE-6 with velour image better than LCD-3 to me), soundstage becomes much wider, slightly deeper and higer, highs become more prominent but more accurate and the bass as a result, seems to be a bit recessed. As for most of the mids, 300-2000hz, it's much harder to tell a difference. I'd say it's really negligible. Maybe it's a bit more transparent, I couldn't really tell you.
The HE-6 with LCD3 pads actually sound a lot like the HD800, but still with better impact and overall midrange (mainly vocals) rendition. Highs might be better, it's real hard to say. Still, nothing images or creates a stage like the HD800.
I think the only big drawback is the bass recession. Unfortunately it cannot be fully corrected with EQ; you simply cannot bring back the depth and viscerality of the bass through EQ, only correct the tone. Maybe when I get back my vintage amps from the cleaner will the pairing be perfect. The HE-6 off the vintage amps I own extends so much lower in the bass vs the mjolnir, and they add a lot of dimension to the bass. So maybe the LCD3 pads with the vintage Sansui/Marantz will synergize perfectly (I'm hoping!).
By the way, comfort with the LCD3 pads is top notch. It's not as light as the HD800, but I think the weight distribution is perfect. And because the headphones aren't quite as large, I don't get jaw-line stress with the HE-6 compared to the HD800. So the HE-6 with LCD3 pads may even last on longer listening sessions. I may even go as far as to say it's more comfortable than the HD800 on my head
Honestly, HiFiMAN should consider making angled memory foam velour earpads. I'm sure they can upgrade their pads for the better in terms of comfort and sound. The imaging and soundstage alone make me think the LCD3 pads may be preferred by many over HiFiMAN's current offerings.
IMO...
