So to answer the questions in your 3rd post, I'll be completely honest, and you should sell your amp on ebay, and with that money, buy a Behringer Ultratone K18000F keyboard amp. These things run at 300 USD according to Musicians Friend, and it's a serious bargain for something that does that job far better than you expect at such a cheap price, and shouldn't take you long at all to get the money for it especially if you can sell the guitar amp.
It has a 12 inch speaker and 1 inch tweeter and weighs about 44 pounds, yet it packs 180 watts, which is what you want in a solid state amp because you need the headroom to be able to crank them without the sound clipping in that horrible way solid state amps do when you turn them up full.
Remember that you need 10 times the wattage to get double the volume (not taking into account other factors like speaker efficiency etc, this is purely about the wattage right now), so can get 50 per cent more volume from the K18000F. But.....my main point is, having 180 watts that you wont ever need to turn up to full is far superior to 30 watts, because you do not need to push the amp into the clipping red zone, which is what would cause your Randall to sound really crap even before it gets particularly loud.
Okay, we have that covered.
Now onto the next part.
Can you use a Line 6 X3 Live with real external effects pedals?
You bet you can. Fortunately, unlike the amp modeling units of years ago, the X3 Live can react very well if you put a good pedal in there.
Examples of pedals you would want to use with an X3, would be an effect not featured on the X3 (such as a pitch shifter) or perhaps you feel the inbuilt noise gate sucks (which I think does and so do many other high gain users) so you can attach your external noise gate pedal, like an ISP Decimator for eg.
That said, personally the only things I would attach to an X3 is an outboard noise gate (which is only really necessary for those who use really high gain, but otherwise non essential for many other guitarists and those with active pickups or a Variax) and pitch shifter.
Basically, everything else, Delay, chorus, overdrive pedals etc, it's all contained in the X3 already
The amp simulations.........well simply put, they will not compare with the real amp they are based off.
I'll explain this in a bit more depth.
The X3 Live can "sound" like a tube amp, but it doesn't "feel" exactly like one though.
What this mean is, you can record an X3 Live, put it in a mix with other instruments, fine tune it a little with EQ-ing, and you will be able to fool people into believing it's the real deal. That is how good it's potential for recording is.
Some people on forum boards post up clips and say "it was recorded through X amp" and then later they admit it was actually done on the POD X3 Live, but no one could tell, because it quite simply sounded pretty much as good as a real amp that was recorded via a microphone. This is partly the reason why I'm buying one myself, because not only do you get such an incredible array of amp sims and effects, but it's simply one of the most powerful recording tools on the planet for recording guitar and when you factor all that in, you can see what great value for money the device is, despite what appears to be an initially moderate-high cost, you truly do get your moneys worth.
Where the Line 6 gear falls down, is when you play live and rehearse in a band.
This reveals the limitations of the amp simulations in trying to get that tube amp sound.
The amp models simply don't have the same amount of dynamics as a real tube amp, and certain other subtleties you get with tube amps, just aren't there with the Line 6 gear.
Even the most hardened Line 6 gear fanboy admit this too, to add weight. Nothing in the amp modeling range I've heard from Boss, Zoom, Line 6 or Korg sounds quite like a true tube amp.
For this reason, you simply wont be seeing many guys who can afford a good tube amp using a Line 6 POD on stage for their main tone.
I've talked to many guys, and I'm not talking about newbies, but guys that have been gigging for years, and they have tried both modeling and tube amps back to back, and what they found is that the tube amps simply cut through better and respond to pick attack and playing dynamics more.
But since I myself, and I imagine you, aren't on the biggest budget ever, I'd honestly sacrifice that bit of tube amp feel for something more versatile, something that doesn't need to have tubes changed which costs money and something that is far easier on the wallet.
Some guys I know are actually running their X3 Live into a tube power amp, through the speakers of their choice, and for them, it brings the tone closer to a tube amp and warms up the sound too.
And how does it tie into the Keyboard amp though, you must be wondering?
Basically, an X3 Live can be run into anything, a guitar amp, bass amp, keyboard amp, PA system, a home stereo system if you have the necessary connections, which makes it a versatile, whereas a guitar amp, well, it only does it's one thing.
Through the keyboard amp, you can turn on the cabinet simulations on the X3 Live and this is what makes the X3 Live able to run into anything, because you can simulate the sound of a guitar amp and speakers through anything you want.
All you need to do, is to plug the X3 Live into the keyboard amp, dial up a guitar amp simulation and speaker cabinet simulation, and compared to your Randall amp, you will be truly blown away by how much better it sounds.
I guarantee you will like the X3 Live because of how much of an improvement it will be over your current rig.