That little blue pedal in the top part of the HD500x board is actually connected with the other pedal board; I was testing it out, hadn't used it with that board, had been running it in stereo in the FX loop of the HD500x as a 'post' amp model multi-effect - chorus/ delay/reverb, etc. Stuff at the end of the chain..
In the pedalboard sequence, the bottom row are the pre effects; that bottom right white/red pedal after the compressor is an overdrive, that cable goes to the front input on the DT25 head.
One other thing worth noting, ISP makes a kick-ass noise gate! That noise gate is awesome; it's the silver/black pedal turned sideways at the top of the board with four cables connected to it. You run your dry guitar signal through it first, and it just tracks your instrument - that way when it's doing the noise gate in the post, it uses that tracking to distinguish between noise you are making with your guitar, vs noise being induced by pedals / effects, etc.
Here's the whole signal chain from start to end:
guitar -> line6 wireless-> noise gate 'pre tracking' stage 1 -> keeley fx loop pedal [loop through Vox wah] -> tuner -> keeley neutrino (envelope) -> keeley bootlegger (germanium overdrive) -> keeley 4-knob comp -> keeley overdrive -> DT25 front input
DT25 fx loop send -> volume pedal -> noise gate stage 2 -> keeley chorus -> keeley phaser -> mxr delay -> (off the board) Zoom MS-70CDR (chorus / delay / reverb)
The Vox wah and MXR delay are not mine; so I still have my eyes out for other pedal options. For now, will probably swap out the MXR and put in the Zoom pedal; it took me some time, but once I got the hang of how to set it up for foot pedal use to cycle through the presets, I started to really like what I was hearing! Technically, if I wanted to expand the rig to stereo or wet/dry, I could do that - the Zoom is stereo in and out. Just what I need! Another excuse to buy another DT25...
As for the wah, I'd prefer to get a wah that doesn't need that Keeley true bypass. I could use the Keeley slot for something else; or possibly to add an on/off to the Zoom pedal. The Zoom is odd, and has it's limits. You set up a list of the patches you want to use, and there is no real 'off' - it just keeps cycling through the list. I set up the list so that every other patch was blank - essentially an 'off' between every effect patch, but it didn't preserve delay and reverb trails. I *think* with the Keeley it might allow the delay trails, I need to test that. (it's powered by the Mondo - 12 pedals total, the Line6 power supply is velcroed to the underside)
I also still have my eye on expensive switching systems; like the crocodile tail, things like that are awesome but, as is this board is sounding pretty sweet with minimal noise, overall the pedals are balanced and positioned well in relationship to each other. Took a lot of shifting around at first! The germanium drive does not like being after other drives, and the second overdrive sounded better after the compressor - like an overdrive / boost. the bootlegger into the compressor is awesome; creamy lots of sustain, and nice drive tones. the compressor holds the volume spikes in check.