Took some pictures for everyone interested.
The Peg Test
tm - One of the main reasons why the MDR-1A is so comfortable.
Ear cup size comparison between the MDR-1A (left) and Momentum 2.0 (right)
Ear cup depth - Tilted drivers on the MDR-1A vs using thicker padding to achieve the same tilt on the M2.
Some quick conclusions about bass (the biggest difference imo between the M2 and the MDR-1A)
The M2 is more neutral than the MDR-1A. Both have same sort of characteristic warm sound. Both share the same transparency.
Songs which lack bass on the M2, have lack of bass.
Songs which lack bass on the MDR-1A have some bass.
Proper high quality music that is mixed neutral, are flat on the M2. Music which has too much bass (poor mixes) have too much bass on the MDR-1A, whereas the M2 now starts to become enjoyable for me. This is otherwise known as a compromise, and either can be fixed via EQ.
In short, listen to higher quality sources and the MDR-1A will reward you with more enjoyment, because the added bass serves to give more to a sound, that is already mixed well.
Looking forward to see how the MDR-1A improves over the next 100 hours or so, I think the bass is only going to get tighter, which would be fantastic. But I've got my ideal bass quantity, now perfect.