I tried rendering a track at 48000Hz - 32 bit, but what was the result?
My VSTi’s sounds were all gone … 
So is this high quality rendering totally useless or should the finger be pointed at the VSTi-programmers (who only allow CD-quality sound output)?
yep. this is vsti fault…
but this only affects sampling freq… you can still use 32 bit!!
I too have found this a bit useless, but for a different reason.
I made a track using the LofiMat effect to gritty it up a bit. What happened when I rendered it? Erm, it smoothed the samples out so they were’nt Lofi anymore - weird!
Seems the only way to record the track as I hear it is to record via Cool Edit or similar whilst physically playing the song (this should also work for you if you still have missing VSTI’s, Man)…
Monotron
Perhaps this is just another vst that cant handle 32 bit then?
Monotron maybe you should do some experiment (if you didn’t already) about switching on/off one or more of the 3 options “Dither - DC-Filter - Soft Clipping” in your configs -> audio -> master? 
I also remember some issue about different rendering options/methods giving different results ( Real vst compatibility - Low - High )
If you do Real VST compatability, the song should render fine.
I haven’t had problems using this option so far.
Sorry guys - should have mentioned that it is NOT a VSTI - just a regular sample…
Have tried some stuff - sounds closest when I render 16bit 44100, but still not great
Just one of those things, I guess - it’s not killing me 
Monotron
I had the same problem with a tune I made, when I rendered with arguru’s sinc the fx’ed track lost all its intensity…
But I don’t see any problem with this, really. Mastering in external software is a good idea nevertheless, and it shouldn’t be a problem to just re-render the tracks that sounds ‘off’ in cubic in stead… That’s what I do anyway. 
This might not help, but on my old sound card (an SB Live! that was half broken anyway), I had problems rendering things right unless I had the sound card set to 48khz in Renoise (regardless of what I actually rendered at). If I didn’t do that, everything got out of tune… Seems like that would all be in software, and not have anything to do with the soundcard, but… whatever.
I work with kX on SB Live! using ASIO mode in 48000 hz, so I render it also in 48000 hz. It always renders fine without any issues with VST and stuff.
The thing is not to render in different rate than we work in.
render your tracks separately and mix them into a proper mixing/mastering software. More control, more accuracy.
rendering was okay here. In every given resolution. I didn’t have troubles with that. An additional multitracker may not always be a better thing for mastering.
Try some “specials” in the master section.
The only thing that i know can for sure impact upon samples and VSTI is using Arguru’s sinc interpolation.
Cubic interpolation is really the most trustable option if you don’t want to compile 44Khz samples to 48Khz.
The sample polishing using the Arguru sinc interpolation routine may interpret samples sort of incorrect or output can be not as expected.