This also shows the importance of a chassis designed to absorb resonances and not pass them to the tubes. Most units use folded sheet metal which is inadequate. Very few preamp manufacturers, except for the Very Expensive ones, use correct chassis.
Same with amplifiers. The cost of a truly high quality all aluminim chassis is quite high unless produced in truckload quantities. Even then it is much more expensive than the standard wood with aluminum top plate or folded stainless steel over cheap metal frames.
Same with amplifiers. The cost of a truly high quality all aluminim chassis is quite high unless produced in truckload quantities. Even then it is much more expensive than the standard wood with aluminum top plate or folded stainless steel over cheap metal frames.