Sounds like you might be better off sticking with something purpose designed for the task, a proper acoustic guitar amp. Do a little research at a good site like Elderly.com and then read up on the owner reviews at HarmonyCentral.com. Various effect pedals combined with a neutral amp should get you where you want to go. If you can't find an amp with reverb you like, a Peavy SRP-16 digital reverb is a great sounding, versatile pedal you can find on the used market with a little patience. The are many ways to get a mult-voiced effect; digital delays, loop stations, echo. You can entertain yourself pretty cheap buying used pedals on Ebay or the sales corner at HarmonyCentral.com. Resell 'em if you don't like what you hear.