InEar StageDiver SD-3S

Quality IEMs. Wonderful build quality - almost feel like polished rocks. Despite the irregular shape, they've been comfortable to wear for long hours and have excellent sound isolation since the housing fills most of the sound collecting part of the outer ear.
I own both the SD-2s and SD-3s and can power both easily off a phone (I use LG G6), an external amp is not necessary. Both sound pretty similar and have a smooth and non-fatiguing signature that is really pleasant to listen for extended sessions. If you're trying to decide on one, I'd say the SD-2 are the more balanced and forward sounding headphone and probably the one most would prefer. SD-3 are a bit darker with slightly elevated sub/lower bass, the upper treble is also maybe a tad more laid back too but not so much that it's detracting.
Either way, definitely recommend giving them try -especially given Thomanns generous return policy.