This hasn’t been my experience at all. Actually unsurprisingly the dynamic range and perceived dynamics are improved a lot. If one measured it, it would be very substantial. Tonality seems unaffected thus far.
Do you have any experience with these Pearl Tube coolers? Can they indeed be wrapped around (very) high voltage 211 tubes and make tge latter actually sound better? Curious in what areas these coolers add to the sound quality or is it only a matter of extending the life of tubes?