Forgive me, I posted this in the wrong section, twice! So, third times a charm, I will try to clean up and delete my old post, since there were no comments (hence me realizing, it's in the wrong place..)

I have messed around with a lot  of configurations since I got my X3L a couple of years ago, and recently  stumbled into the 4-cable method, that has been working  pretty well for me so far, with my amp.

Well,  that led me to a variation in the 4CM, by plugging the guitar into my amps front  input, then putting the POD into the amps FX loop, and a Keeley 4-knob compressor into the FX-loop of the POD.  This does wonderful things for the sound in terms of controlling level  spikes, packaging up the tone nicely, and a sweet volume  containment of all the wah models. Put them through an analog limiter/compressor, and they sound  way better!!

Ok,  so my dual FX-loop, with an analog compressor rig:

1.  plug 1st cable (into your guitar) into your amps front input

2.  plug 2nd cable from amps FX-send (out)*  to POD guitar in. (You might  need to set the input pad "on" depending)

3. plug 3rd cable from  POD 1/4" out to amps  FX-return (in)*

4. plug 4th cable from POD  FX-send(out) to  outboard compressor input

5. plug 5th cable from  POD FX-return(in)  to outboard compressor output

*  note: I  think on some amps (like the Fender hot rod series) these fx  loop in/out jacks are labeled "preamp out"  and "poweramp in"

**note:  make sure if your amp has an FX-loop dial, to turn it all the  way to  100% mix.

Ok, so programming, here's the intent I  go for with tone 1:

- stomp set up as a classic  distortion or tube screamer, or tube overdrive

- "comp" switch  pedal set to turn amp model on/off

- mod set to the new "script  phaser" which has tap tempo, or barberpole phaser in stereo

- amp  model set to something like "cali crunch" or "class a 30", or whatever you want.

--then, be sure on the amp page to turn off the cabinet. Scroll to the end of the guitar cabs to the selection "no cabinet", which also turns  off the mic

--- this amp model is used  as an extra stomp pedal, and since amp models have nice eq controls,  think of it like a totally expanded distortion pedal, with low/mid/high  and presence controls on most every amp model. Since you are not using  cab or mic models, this is subjective to what sounds good coming out of  your amplifier at your place!

-Compression / Limiter: Start with  setting the outboard compression amount less than 12 o'clock, and  set the master  volume out to between 2/3 and 3/4 up. On the  POD, set the FX-loop  mix to 100%, and set the return to +4, or +8, or +12db  boost,  depending on how you set the external compressor. My Keeley has 4 knobs :  compression, master volume, attack speed, and input trim. Typically set  the attack and input trim to the same as the Keeley 2 knob, which is  fastest attack time, no input gain reduction. Sometime I ease up on the  trim (input gain) to get more clarity, the higher this knob is set, the  faster the pedal squashes signal. As I turn the trim down, it is cutting  input signal, adding headroom, and reducing the need for compression  until higher levels, regardless of the master output setting. In actual  sonic audio terms, it makes the treble increase since the treble freqs  are the first to spike from the POD, they are the first to get cut down  by the Keeley, softening the tone. Rolling this trim back can actually  serve to dial in the right amount of bite to softness ratio. More trim  gain reduction, more treble increases. Less input gain reduction, more  treble gets squashed and softened!

Placing that  outboard comp in the POD's fx loop really does sweet wonders for amp  models overdrive and stomp pedals too. You can now use all master  volumes as a type of tone control, rather than really messing with your  output volume. The Keeley is kind of expensive, so this can totally work  with an 80 dollar boss cs-3, or mxr dyna/super comp or whatever you can get your hands on.

The reason I say  you can use the amp models drive and master volume, plus the stomp  models drive and gain setting as "tone" control rather than volume  control, is because the outboard comp (keeley, etc) is acting as limiter  and also a compressor, so the sounds are all louder than the keeley is  allowing to come out, causing a squashing of everything. The more you  turn up the volume and drive and gain, the more it squashes! It actually  can create some wild effects,.

Regarding  "pre" and "post" settings on the POD: these now matter! If you have not  used the FX loop previously, these setting didn't play as much of a  role in drastically shaping your sound. You can set several of the FX on  the POD pre or post. In particular, I like to use the weird analog or  modulation based delays sometime, but they can also do a weird runaway  sound effect that can cause some strange volume spikes. Same for alot of  the more fun mods, like phaser, flanger, etc. If you experience  unwanted volume spikes / issues with these effects, they can be set to  "pre", which is before the effects loop, IE, before the outboard  compressor (keeley). This forces these effects into the level control of  the analog comp, which can be nice. Then, digital delay and stereo delays  sound great as "post", same for chorus and reverb

Mind,   you, this is all "tone 1" only. No amp modelling, no mic modelling yet.

Then, to also send XLR with amp and mic modelling, you could then do  something like,

- attach the other  1/4" out from the  POD to the AUX input on the POD,

- set tone 2 as AUX  in,

-  mute tone 1 to the XLR outs and

- mute tone 2 to the 1/4" outs.

-  Set tone 2  with noise gate, POD's compression

**(no FX-loop, can  only be used mono on one  tone or the other), and then also

- use  a clean amp model with cab and mic  emulation.

- Give it some  room in the amp setting.

- Maybe use the new  "dimension" mod for a  nice subtle chorus like stereo effect, and

- a small  amout of a  big reverb (less than 10%) of something like 'cavernous'.

The  main  thing I REALLY like about this rig, is the outboard (keeley)  compressor  in the POD's effect loop. It makes the wah models sound  good. All of  them. No more noisy weird volume boost. Play with the  master volume on  the outboard comp, play with the amp vs. line level  send on the POD, and  get those right, and the outboard comp acts as a  nice analog smoother,  limiter, which holds back the weird wah volume  peaks, plus, since the  POD is in the FX loop of the amp, the noise gate  kills any extra amp  noise. Even kills a 60 cycle hum I get from the  clean channel of my  crappy solid-state Marshall. I can't imagine how  good it sounds on a  nice tube amp!: