Leben CS300XS Tube Rolling

Of course there are older threads, here and elsewhere, that cover the subject. But I’m looking for fresh takes from new users (and given how quickly used units move, I’m guessing there are a few of us around) as well as feedback from seasoned experimenters (maybe even some dating back to those mind numbingly long threads of 10+ years ago).

Some say the Leben CS300XS is responsive to different tubes, both EL84 and 12ax7. Others say only the signal tubes noticeably impact the sound. Given that versions of the amp have been around for ~20 years, this seems like something that should be already settled, but here I am…

New production or NOS and no hard budget, I’m open to trying anything anyone else enjoyed. What am I trying to achieve? Occasionally, I hear some random graininess and/or hardness at higher volumes (could this be tube related? I don’t know). Beyond that, I’m really looking for anything that brings more of the Leben’s great qualities forward (like when I added A23 cables to the mix, *everything* improved).

Speakers are Klipsch Forte IV and sole source at the moment is a Chord Qutest DAC. Thanks in advance for any advice/help you care to share.


I had to send my leben for repair after borrowing some vintage amperex el84s from a tube enthusiast friend of mine, later found that one of the tubes was bad and that caused an issue in one of the channels. Just a caveat to make sure you know what you are putting into your amp!

@roncagg you read my mind. My first Leben developed an issue shortly after the first tube change (new production tubes though). That unit remains in repair limbo, so I still have no idea how the tubes could’ve damaged the amp (which of course makes it tough to be more mindful in the future).