I've done a comparison using three different sets of preamp tubes. Now in this video I've switched the first three preamp tubes, which are used for channel 1 and 2 of the EVH 5150 III. Channel 3 isn't used in this video (it uses preamp tubes 1,4, 5 and 6). Does anyone have an idea what the "Mesa Chinese 1" tubes are? Couldn't find any info about those. Anyway, what do you think of the difference in sound and what is your experience with replacing preamp tubes? As mentioned in the video, I think the difference is a bit overrated. Also would like to mention that the sound 'in the room' wasn't really different too. I don't have a lot of experience with different tubes and I'm sure a lot of you have more experience with them, so I'd love to know if any of you have different experiences with them and did you have any (preamp) tubes that actually made a lot of difference in sound?