The blon 05 has better quantity and quality of the bass compare to t4, but against to blon 03, the 03 has more powerful, warm, thickness on the bass.
The 05 bass can go more deeper than 03.
The blon 03 has most mid bass( which can be bloated) body follow by 05 and t4.
The 05 has most upper mids boost(which make it shouty and vocal sound too thin) follow by t4 then 03
The treble on 03 does the best jobs for me, as the treble on the 05 and t4 are too bright(but it bring kind of detail and space feel)
Sound stage 05~03 > t4
Details 05~t4( through treble boost)~03
Overall the tonality on blon 03 is my favorite, it has good low end, creamy and smooth mids, great treble, as the 05 are too shouty on upper mids and thin vocal make it not my cup of tea( it is even shouty and thin vocal compare to t4), and for t4, it is good, but too neutral, boring for me.
I will be getting he t2 plus soon , I think for under 60 usd dollar, the blon 03 will be my choice, and t4 is good, but for me bring, for blon 05, I think the tin t2plus will be really similar to that, with more better upper mids and treble.