Hi Lew, I've had the screamer and fireball for ages and if you want to get the best out of a screamer than put it through a decent 212V/ 412V cab. I've had good results with my 212V - samples below.
In my opinion, once you've tried these amps there's just no going back, you just want to try more ENGLs and I'd be interested in trying the invader and savage next. They have a much tighter low end than rectifiers and cut through the mix better. In direct comparison of the screamer to the marshall JVM for instance, I think the highs are much more controllable, less shrill, much easier to get a decent tone even with bright pickups (eg painkillers), the high gain channels are also a lot less noisy than my JVM (when using the same gate on both).
You have to love the very transparent FX loops with these amps and I disagree with someone above who said they don't take OD pedals well, I've had very good results. Using an overdrive pedal I can quite easily make the fireball a 3 channel amp- clean, crunch (clean channel with a good transparent OD which doesnt affect your tone - I use a hotcake), and ultragain channel - for metal / leads. These amps clean up amazingly if you know how, I often use my screamer on channel 4 and if you switch to split coil pickup with the volume down u can get a good clean if you want 'pedal free' switching. Despite having the expensive Z5 footswitch, I've never needed it.
Screamer clips
http://www.youtube.com/watch?v=HwaRzeUWoLE&feature=channelhttp://www.youtube.com/watch?v=d_Sc6TP1GBk&feature=channelFireball clip
http://www.youtube.com/watch?v=kN2vcwTt9sQRemember the advantages of 50w vs 100w amps by the way, less expensive tube replacements in the long run! And as someone said above the 2nd crunch channel when cranked sounds Godly, blows away my JVM. Good luck with your purchase. :band5: