I've used individual spring reverbs as well. E.g. I have separated out the drums mix, vocals, and acoustic guitar on individual springs, so the signal coming back from the reverb wouldn't be as "muddy." If you have a stereo reverb, try using individual channels that way and see if you like it if you have enough effects/aux send/returns.
Also guitar pedals are designed for a relatively low level signal going in, and they often have volume knobs directly on the output.
For the input you'll have to make sure you don't overload the pedal. On the output, you should keep the volume knob as high as possible. As pedals usually have a volume knob right on the output, these are can be 50k to 100k ohms, and depending on the input impedance of whatever you are driving, could affect the sound in a bad way. I.e. the lower the volume knob, the higher the impedance your input is seeing. Your effects returns are probably in the range of 10-50k.
(The pedal isn't a problem for your guitar amp, which expects a pretty high impedance output from your guitar pickups.)