When i put the same fx (Renoise distortion in this case) with initial settings in track fx chain and in sampler fx chain, they dont sound the same. The sampler one sound dirtier and overdriven in bad meaning. I think this is a bug.
Definitely confusing. It’s the Track Headroom which makes them sound differently (See “Song” -> “Playback & Compatibility Settings”).
Track Headroom is a pre track volume and thus is applied before the Track FX’s Distortion in instrument 1, but is applied after the Track FX’s Distortion in Instrument 2.
Instr 1: Sample Playback -> Sample FX Chain -> Track 1 Input -> Track Headroom -> Distortion
Instr 2: Sample Playback -> Sample FX Chain -> Distortion ->Track 2 Input ->Track Headroom
We also can’t apply the headroom before sending it into the sample FX chain, because this would apply the headroom twice then.
taktik, maybe adding a checkbox to the Renoise settings “-6dB beginner’s headroom” that can be unchecked, so not every new project needs to be setup first?
Thanks for answering.Maybe you can add possibility to set headroom per track 
Or, better, input gain control in distortion plugin.
How about just a list of differences in the <can’t use instrument on multiple tracks at the same time> area
Herodotas: simply set pre effects chain volume of the instrument effects chain track to -6db, and the driver is exactly the input gain