I traded my H&K Tube Meister 18 for the 36 watt version. I tried a matched set of these RFT EL84 s and couldn't come up with a nicer tone with any other tubes I swapped out. The best preamp tubes that I own for this amp were 3 12ax7A/7025 similar to the Tube Store Preferred Series. So... for the Hughes & Kettner Tube Meister 36, RTF EL84/6BQ5 with 12ax7A/7025 (Preferred Series) preamp tubes. I posted this because people are always asking what to put in their Tube Meister. This setup will give you rich sparkly cleans, and a nice smooth overdrive. Keep the volumes at least half to get the power amp section working, and adjust volumes with the power soak buttons and gain controls.