Here's a little trick for hardware synth owners who want to try out xenharmonics. Even if your synth doesn't have proper tuning capabilities, you might be able to get some EDO's (equal divisions of the octave, or equal temperaments) out of it. This trick works if your synth has an option called pitch slope or pitch keyfollow.
For example, the Roland MC-808 Groovebox, not your typical xenharmonic tool, can do 5/10/25-EDO, 8-EDO and 11-EDO with this function. In the manual, Roland calls this option pitch keyfollow.
Pitch slope is a different name for the same principle. Several KORG synths including the microKORG have it.
Here's how it works: you find a setting of the slope that produces a pure octave, spanning not 13, but - for example - 6 keys. Now you're playing in 5-EDO!
If your hardware synth doesn't have these scaling options, you can also check if it's possible to use a fine-tune option. But this method takes a lot more programming work, and only a fine-tune option for every individual key of the keyboard in a patch is flexibile enough.
A final tip for machines like the MC-808: these also have samplers on board, which means you can load timbres to match the tunings you like to play with. The easiest way to create tailor-made sounds for 5-EDO, 8-EDO etc. is to use the free FMTS2 by Xen-Arts.