I have been using the R-50(reshelled) on and off for the past year and half. Well its a long story and the build quality was horrendous.
STORY >> I had a GH-ERC-DMS TWFK iem( B2 clones) which were the best earphones under $100.00 that I got used from another headfier (were replaced under warranty from Japan)... and they were pretty analytical with next to no bass...
I tried to get them reshelled by Rob at In ear custom( old name) .... the shipment was stolen and by chance - ever generous Rob bought me an R-50. It had an absolute top-class sound with adequate bass and was a much refined version of the GH-ERC-DMS, however the build quality broke it for me .... and the left channel had an internal disconnection.
Rob offered to reshell it for me and put on shure SE-535 MMCX connectors FOR FREE!! ... I have been using the reshelled R-50s for over a year and I am very happy.. Though his custom IEM finishing has gotten way better today ... I am proud to have done business with a gentleman like Rob.
Eitherway to answer some of your questions I read about the previous few pages...
1. On amping - I do not think Amping will do a TWFK any good, especially one with with such high sensitivity ... and I think its about the VFM on purchasing an amp if R-50(reshelled or otherwise) is your main music driver ... I just can't do anything but laugh at anyone using a CMOY tube for driving an armature!! oh the impedance mis-match ! oh the horror ...!! thinking further about it .. I can only be scared of the BA drivers in your respective R-50s!
2. Source/DAC - this on the other hand is where I would ask any of you to concentrate - an ODAC will do you great wonders ...
3. File quality and treble - I think if the file quality is good enough, the R-50 will in turn be good and some of the sibilance and brightness will go away, perhaps even resolve it brilliantly like an RE-272 does! after all this is what 'neutral' means .......just a reflection of your audio chain! If you still decide to use horribly compressed or poorly mastered files - try to get yourself some shure yellow foams - they make the treble way less bright!
All the best guys ... .