FWIW I don't think microphonics in tubes is going to cause a 'ringing' in the 600 to 800 hz range. It would be much more noticible in frequencies above 2000hz IMHO.
Sounds like you may just be hearing the difference between the sonic nature of some tube pre-amp's which can be a tad more forward in the mid-range and quality ss which are usually much more linear. Also, consider that tube selection is critical both tonally and clarity wise. You may just need some different tubes in the pre-amp.
Sounds like you may just be hearing the difference between the sonic nature of some tube pre-amp's which can be a tad more forward in the mid-range and quality ss which are usually much more linear. Also, consider that tube selection is critical both tonally and clarity wise. You may just need some different tubes in the pre-amp.