Stay away from chains of digital effects. I'll kill your tone and linking a lot of stuff together can easily turn the signal to mud and create noise. It's also a bad idea putting distortion at both ends of the chain, especially digital. For the price of all that you can get a decent valve amp that can roar like it has a solid pair.
Also, if you want a clean solo sound, you're not going to be distorting it. A little overdrive might be good, but you'll want it as pure and analog as possible to preserve richness.
For clean solos I like guitar-->maybe a little reverb and/or delay-->speakers. Nothing more, besides setting the eq.
By synthesizer do you mean like something for guitar or something like what Pogo plays?
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-A.H.