OK, is everybody ready to go NUTS seeing if they can hear differences in tubes???? Well, you've come to the right place! I just did some serious experimenting with tubes in my Komet Concorde. I found a decent spot for my GT55 mic, i/2 foot in front of my 2-12" /13 closed back cab, with greenbacks. The mic never moved, so you are only hearing tube changes. One thing- I was using the Komet Airbrake attenuator, down 2 clicks. Amp was in gradual mode, on about 5. DISCLAIMER- I did this to display the reality of how much tube changes do and don't affect things... it's subtle! but cumulative... I'd recommend downloading the mp3, then loading it in an audio editor so you can see the waveform, then you can chop it up and listen to the various clips back to back. I did spoken commentary too, so that should help. Listen on good speakers or high quality headphones if possible.... Also, sorry about the tuning, it was a little dodgy at times. The amp came stock with Sovtek LPS 12ax7's in V1,2, and 3... winged C 34's in the power section. I quickly switched V1 to an Amperex. The rest I left alone, and that's how I started these clips, with that combo.. the first 4 all have the winged C's in the poweramp. For the 2nd clip, I switched v2 and v3 to Tesla E83cc NOS tubes from Mike at KCA. I heard an immediate slight clarity improvment (less "blurry") so I left them in for the rest of my tests. For the 3rd clip, I switched V1 to a Mullard 12ax7. Notice how the Amperex was slightly more "full range" and broad, and the mullard is fatter and more forward in the mids. Sounds Like we know Marshalls (I know, it's not a Marshall) should! Clip 4 is a new Tung-Sol 12ax7 in V1- nice tube! A little more "sizzle" on top than the mullard, and this guy hung in there really nicely I thought. Fat, sizzle, all there. Clip 5 is the Mullard in V1 and the new GT Mullard EL34M reissues in the poweramp. Clip 6 is the Tung Sol in V1 and NOS Tesla EL34's from Mike at KCA in the power section. Clip 7 is Mullard in V1 and the Tesla 34's in the power section. This combo had it all. What I learned from this- Winged C 34's sound really good, in this amp! I liked the Mullard in V1 overall, a little better than the Amperex... but suprise suprise that Tung Sol sounds really great I think, very clear and fat. The Tesla E83cc's added a clarity to the v2 and v3 positions that was pretty obvious to me, so that was a plus. The Tesla 34's sound woody and warm and clear, nice vintage sounding tube... The GT34M's were similar, but not quite there. Not bad though. I'd use the Winged C's for some stuff and the Teslas for other stuff. Liked them both. go here, click on "Komet tube experiment": http://music.mp3lizard.com/petethorn/ Happy listening!