Hello MF members. As we all know, there are always a lot of threads pertaining to tubes. I would like to just share a few things and I hope it will be helpful. First off, a lot of questions are directed at the "high gain" Marshall's like a DSL, TSL or 410. Please be aware that these amps get all of their tone out of the preamp stage. I cringe when I hear someone with a DSL asking how they can get "better power tube distortion?" If you have a DSL and the power tubes are distorting, I don't think you will like what you hear. DSL amps (and other high gain Marshall's) use four (or more) preamp tubes. V1 and V2 are the gain stages. V3 (A and B) are the Tone Stack and Cathode Follower. V4 is the Phase Inverter tube for the power tube section. V1 will make the most noticeable difference in tone and gain. I always say that you want to put your very best tube in V1. The DSL can handle a pretty hot 12AX7 without farting out. I used to be a little conservative about the V1 tube I used, but over the past year, I tend to go with a hotter tube if it fits the player's needs. I use a more moderate tube for those whose playing style dictates it. Note: In Plexi's, JMP's and JCM 2203/04's, V1 is the main tube for gain. Half of V2 needs to be considered as well, so I still recommend a good tube for V2. Here is something that has me perplexed. Current production tubes are not that expensive. I think any guitarist that has more than two years playing under their belt needs to have a nice stash of tubes to fall back on and also to experiment with for tone. I think every player should have a budget that allows for multiple 12AX7 tubes. They shouldn't be purchased "as needed." I have said this before, "Every tube amp player should have a complete set of tubes to be used for backup purposes or troubleshooting." If you own a Marshall or other tube amp and you are running old tubes, because you can't afford a new set, you run the risk of damaging your amp. If you are lucky, a fuse will pop when a power tube blows. However, I have seen more serious damage such as fried valve sockets and burned components. Again, all tube amp owners should have a complete backup set of tubes. Now back to 12AX7's. You should try and get yourself a JJ ECC83 (same as a 12AX7). Also, a Tung-Sol and a Mullard RI. You can round out your set with a Shuguang (Chinese) 12AX7. The Shuguang's are usually loved because they are high gain and are a favorite with metal players where a good clean isn't a must. Most of the guys I hang with have 30 to 40 12AX7's. Enough to last them for a good long while. Most of these tubes were bought over a three year period. Most of these tubes are NOS. However, I won't go into that, because most of you use current production (CP) tubes. I think a good player would have two each of the preamp tubes I have listed. Having some Electro-Harmonix tubes handy would be good also. The EH tubes can be used as an economical replacement for V3 and V4 (especially the PI tube). To "roll" tubes in a high gain amp, you want to have V3 and V4 selected. Therefore, take a couple of EH's and put them in those slots. Put a Mullard RI in V2 and then roll the JJ, the Tung-Sol, Shuguang and even another Mullard in V1. Once you find the one you like, pull V2 and roll your tubes in V2. Once you find the tube you like, then you have your V1 through V4 selected. If you want to get picky, try rolling V3 and then V4. You might notice a very slight difference in tone by rolling these slots. My friends and I like to run a lopsided, high gain tube in the PI. This is because the power section is asymmetrical by nature and a lopsided PI tube will help enhance this. An amp with an asymmetrical signal has a lot of even order harmonics and this is what you want. This goes against what EURO TUBES states. They push their customers towards a "balanced" PI tube. Trust me, you don't need this. I will say that there is a small difference in tone between a lopsided tube and a regular one, but if you are used to rolling tubes, you will hear a small difference. Power tubes tend to sound similar to each other when they are cranked. I run NOS power tubes and CP as well. A while back I did a review on how Sylvania Fat Boy 6CA7's (same as an EL34) compared against EH 6CA7's. At lower to moderate volumes, the NOS were better, but going above 5 on the Master Volume they both started sounding very close. I will say that there are some cheap power tubes that are thin sounding no matter what the volume level. I bring this up, because power tubes in high gain amps are designed to be ran "clean." If you use a cheap power tube, you will notice it regardless of the volume level. Look for a well made tube that are frequently recommended. Stay away from the el cheapo tubes. It's just not worth the heartache it will cause. In closing, preamp tubes will make the most change in your tone. Power tubes just add a little. You should own a complete backup set of tubes for your amp. You should know that V1 is the most important preamp tube. For the best sound you can get out of your amp, V1 should be tested for microphonics. You'll want V1 to be as quiet as possible. Some tube companies charge $2 to test for microphonics and high gain. This is well worth the price for a V1 tube. Remember, asking about which CP tube is best should be answered by YOU. Buy some and try them. I had a customer recently tell me that he had some power tubes that didn't sound right to him. However, he swapped V1 and the power tubes kicked butt. Tubes that sound good in a 2203 may not sound as good in a DSL. You are limited to the tones you can get with CP tubes. (Yes, NOS tubes offer more tone shaping compared to CP.) For the most part, rolling tubes is like the icing on the cake. If you are happy with your amps general tone, the speakers you use and the guitar/pickups that you use, then rolling tubes is like the final piece of the tone puzzle. I hope that you found this to be of some help.