Ok, so since everyone's going to bust my balls about the clips part, I DID record some fairly quick, dirty, and sloppy clips before and after the swap. The playing sucks (I was making it up as I was going along so the riffing is especially iffy ), but they get the point across. I just have to sort out some FTP issues before I can get them online.
First, the tubes - I went with Groove Tubes EL34M's (Groove Tube's take on a Mullard xf2) largely because the GC cupon I had wouldn't cover Mesa tubes and of the tubes they stocked these seemed to get the most consistent good reviews I could find on the net. Since they were $50 off, I basically grabbed a quartet of power tubes for $20. Are there better options out there? Sure, but not for the price, so this seemed a great way to see if I liked them in a Roadster.
I've only gotten in limited playtime so far - first, some tracking right after I swapped in the tubes, and then some low volume shredding before bed last night where I couldn't push them because my roommates were trying to sleep. So this is a VERY preliminary first impression.
First thing that jumped out at me when I swapped them in, switched to EL34, and flipped it off standby? HOLY SHIT MY AMP JUST GOT LOUD. Seriously, I don't know if the tubes themselves were particularly hot, the JJ 6L6s were particularly quiet, or if they were just getting old and the volume had been degrading, but I went immediately from a comfortable "loud but apartment safe" recording volume to a point where there's a slight hiccup on the lead line on the EL34 take because my roommate Annie knocked on my door and walked into my room to inform me the whole house was shaking and ask if maybe I could turn down a bit (I had to frantically wave her off and try to signal "one second!" while sustaining a note). I've never had my roommates complain about volume before, it's actually amazing how well our house deadens sound, so that's really saying something. It was to the point where I almost had to wonder if the master got nudged a bit when I moved the amp to switch tubes, but I think it's about where I left it, so I think these tubes really were just way louder than the 6L6s.
While tracking, I was actually surprised how similar the amp sounded with EL34s. On my Single Recto, swapping tubes made a shocking difference, especially to the high end - it immediately got way crunchier and in your face. Here, it was a lot more subtle. You can definitely hear a difference (especially in the clean, where the midrange seemed a little more coherent and "forward" and punchy, whereas the 6L6s were a bit more open), but it's much more subtle than I expected. The only difference in the recording I did was I slightly nudged the Nady RSM-4 I was using for the lead part - I repositioned it as well as I could, but it's not perfect. The SM57 for everything else, however, didn't move.
Jamming later that night... I don't know if the tubes needed more time to burn in a bit, if something about the volume jump was obscuring differences, or if I was just less distracted (i.e - not wearing headphones) and the change was more pronounced in the room (or largely outside of the areas where the respective mics were most focused), or even simply because my initial comparison was using settings for 6L6s and I started tweaking as I played, but the lead tone definitely had a different response to it. The low end wasn't as smooth and had a bit more "grit" to it, the high end was more open, and harmonics seemed to jump off the fretboard quite a bit easier. This is again my initial impression and is subject to change upon further experimentation (and more volume ) but I found myself thinking that the sound I was getting was actually relatively close to what I'd hoped to hear in a Stiletto - tighter low end, more harmonic sizzle in the upper midrange, a bit more forward of a midrange, but still with a pretty Mesa-like character to it. It really does have a sort of modded Marshall vibe to the sound - 6L6s are rounder and more balanced (and on Channel 3 make me think instant Petrucci), whereas with EL34s it seemed a bit more like something Lee could get on with, but that I'd also enjoy. Also, raising the presence on the 4th channel seemed to work better with EL3s than with 6L6s, as well as (surprisingly) lowering the gain - the lower gain response seemed a bit more even than it did with 6L6s.
Anyway, I'll try to get clips up tonight or tomorrow, and I'll definitely keep doing some more experimenting. So far, it's not a night-and-day difference, but I'm intrigued.
Huh! I might have to change the tubes in my Digitech GNX3000 to EL34s!