I also have the LG V30 as well as a Sony A55. My desktop setup consists of a Liquid Spark Dac and ancient at this point JDS labs O2. Retuning the Spring 1/2 bass requires permanent mods, perhaps playing with the restrictive venting membrane and/or volume inside the shell using silly putty/blue tac. Since we cannot alter the driver, all you can do is alter the front vs back air space and flow. I know someone else said removing the screen improved it, my opinion and experience says unlikely especially since lower frequencies can permeate through materials easier. Maybe I am biased, but I consider it a placebo. If someone hears an improvement who am I to discount that though.

As to the Sony foam plugs, I removed them from one set and kept them in another set. It has been a while but if I recall removing them is essentially like turning up the contrast knob. You can hear the upper end sound a little less controlled and lively, the mid/treble hump narrows in width and increases amplitude 2-4db rising more towards the presence region. If you remove both the screen and the foam plug its adds another 3-4db to the peaks shown in this post. I prefer them stock.

This is very helpful article, and thankyou for it! Could you say a little more perhaps about the nature of those MH755 removable plugs?

Yrs hamfistedly,
Warbs