I had heard mixed reports on the benefits of cryogenic tubes. A local dealer had claimed a customer had some tubes done, and they sounded bad. He didn't say where they were done, and I think they were power tubes.

The two 6H30 Electro Harmonix gold pin I bought sounded good straight out of the box, remember they replaced the same brand tubes, but not cyroed, with 7500 hrs on them. At around 50 hrs they got a little bright sounding, settled back down by 100 hrs, and at 200 hrs my system has never sounded better. Clarity, extension with detail in the highs, smooth, with a good wide soundstage. Depth seems better too.

Any other changes had been before the tube swap.I would recommend trying a set in a preamp, I couldn't be happier.