Hey guy n gals, long time reader but the time has come to post,
Been watching my Synchestra DVD.....

Does anyone have a clue what the make/model Devin’s guitar splitter is?

If he runs the 5150 separate to the GP-100 were is the power amp for the GP-100? Does the splitter have power amp in it?

I’ve been trying to find one for a while and I’m truly stuck.

If it's the one I think it is, it's just an input splitter, it a JDI cost about 1000 bucks Can. Takes one guitar input and splits it to 7 outputs, with ground lifts and phase and each channel. You could just record FX boxes direct, you don't need an amp for them. A splitter like that won't help you live much, more for studio recording.

ah, didnt realise it was just for recording...... whats the best way to get the ambient soloing sound outa my 5150 and gp-100 for live stuff?

Well I believe live he splits his signal that way as well. Now you can also do this with simply an a/b/y pedal/box, such as the morely a/b/y pedal. This can act as a splitter in the sense that you can use your 5150 as primarily a dry signal, with perhaps even a tad bit of delay in the fx loop (such as with a GMajor or little boss delay pedal), & then lessen the output signal on your gp100. When using the gp100 without a poweramp though, I would recommend not leaving the input past 10 O:Clock or so, as to not over saturate things.
A splitter will do the same thing really, with the exception that you can alter to level post GP100 with the splitter while still leaving your output pretty seemlingly higher. The point of the gp100 in this situation is not to act as much persay as a second amp, but more an ambient texturing to the dry signal. When played together, you have a dry very powerful signal coming right at you, with the gp100 D.I.'d into the board, so then you have all this ambiance surrounding this dry singal now. So literally. A dry signal coming right at you & a stereo wet signal coming at you through the speakers. Real nice for lush sounds.
Scott is the man when it comes to knowing about gear & it's purposes though, I am sure he can enlighten you more.
-Brent