I am replacing two tubes (ecc88 type) in a preamp device I use with my stereo, and read about "cryogenic treatment." Does anybody know about the value of this? Also, has anyone used that type of tube and personally know what sort of difference it makes (if any) to sound output? Below is what the distributor says about it: Cryogenic treatment is a process where a product (VACUUM TUBES) is tempered in a deep freeze process(-300F) for 48 hrs. This process produces a permanent change in the metals inside this product making it stronger and longer lasting. Tools, instruments, knives, razor blades, machinery parts have been Cryo Treated for many years.Why do this to tubes?Tubes are mostly metal inside so Cryo treating tubes has the following benefits: permanent change in the metals at the molecular level(more uniform grain structure of metals), longer lasting, tightens internal parts of the tube allowing for more efficient operation. SONIC IMPROVEMENTS FROM "CRYO TREATED" TUBES: LOWER NOISE FLOOR,lower distortion, extended frequency response at the extremes, greately increased resolution and transparency. You will hear information from the recording you barely, or never heard before, especially at the back of the stage! Bass response is greatly improved, treble is sweeter but more extended.