“I recently purchased a new guitar amp. It has an effects loop I want to run my chorus pedal through, but it distorts. What can I do?”
The problem is that your amp is sending a line level signal out the effects send. And it’s also expecting a line level signal back in. Your chorus pedal, on the other hand, is designed to accept instrument level signals, which are generally much lower than line level. Instrument level signals are what comes right out of your guitar or bass, before going through a preamp. These signals are too low of a voltage to connect to most line level gear (including amps) so they go through a preamp first. A preamp is built in to most guitar amps. It’s the first thing your guitar signal goes through on the inside of the amp. Your amp is overloading the audio path in your pedal because the effects loop is sending the signal out after it has been through the preamp. In addition to the overloading occurring in your pedal it is likely the pedal is not returning a hot enough signal to the amp for it to operate optimally either.
Some amps have variable level controls on their effects loops, which you could use to better match it to your pedal. Many amps do not have this though, which leaves you in a tough spot. You can buy or build a device to better match the levels between the two coming and going, but by the time you spend that money you may be better off upgrading your pedal to an effects processor that will work with line level signals. Almost all rack mounted pro effects units will work fine, and there are many newer pedal style processors that work well at line level or instrument level. Contact your Sweetwater Sales Engineer to discuss what’s best for you and your application.