Hello. I am thinking of trying to run two amps at once. It appears I have a few options:

A splitter pedal- seems to be the best bet but it's the most expensive.

Or using a stereo pedal- I heard the Boss tuner pedal can be used for this but I also
heard it results in tone loss or buzzing or something? I already have a DD3- it has two outputs- would this work?

Or just using a cheap Y-splitter cable- is this sketchy or dangerous?

Note that I'm mostly interested in running both amps constantly for big sound, not so
much on the A/B switching stuff.
I've read a bit about ground loops, I understand I could get injured or break an amp... what exactly are they, how are they created? I was thinking about this Morely one... 50 bucks on musiciansfriend:


It gets poor reviews from some, but it seems to mostly be from people who want to play one amp and then swtich to another... would this one be okay if I just want full blasting out of two amps? Anyone have any experience with this one, or could reccommend a better one for about the same price?