Engl SE 670 EL34
After exhaustive forum research I resolved to purchase and try this tube in the PI slot after a recent lacklustre service (the tech replaced 2 worn stock engl/jj tubes with Electro-Harmonix, I don't think they are quite right for my amp)...made a noticeable difference but still wasn't quite right. I then subbed it into the gain driver slot and wowwww..... The hedonistic saturation was reigned in to a much more articulate and focused yet raw growl without thinning the tone! The gain can be run much higher without sounding like a broken theremin recorded at a heavily clipped level and the hissy top end is completely smoothed. Absolutely love the lower mid punch shining through now on this amp and the right hand attacks on my 7 & 8 strings make me smile again. I am now searching thetubestore for replacements for the ehx tubes and a good quality long plate for the PI (and just a few to experiment with). I think after having done some research that this would be more conducive to the tone I am searching for. Great service, great turnaround from order processing to delivery (to Western Australia) and great packaging, thanks again! 4.5 stars because there is always room for improvement.