Once i tried wearing my IEMS with a over the ear headphones, the isolation was surprisingly good. You could try those sound isolation headphones over your IEMS if you don't mind the bulk.
I generally don't enjoy IEMS as I find them too uncomfortable. I have a custom as well which is uncomfortable in the start, but once I got use to them I just forget they are there. But they are still a pain to put in and remove.
what do you need the isolation for?
Once i tried wearing my IEMS with a over the ear headphones, the isolation was surprisingly good. You could try those sound isolation headphones over your IEMS if you don't mind the bulk.
I generally don't enjoy IEMS as I find them too uncomfortable. I have a custom as well which is uncomfortable in the start, but once I got use to them I just forget they are there. But they are still a pain to put in and remove.