Hello Binyomin, yes I use the compressor quite a bit with the Diamanté and the Hammond 44 not so much with the Hammond Hyper it tightens the sound up nicely. I am pretty happy with my set up and only have plans to replace the volumn and reverb pedals. I use an Ernie Ball junior and there are voids or drops when I do slow swells and sometimes, I am planning on getting Mission engineering pedal to replace the EB pedal. I also want to replace my Cathedral reverb pedal by Electro Harmonixs with a Eventide space reverb. There are a lot of trial and errors with pedals when it comes to using them with a Melodica. definately try the I line boost transformer first. It may do the job and there would not be a need to buy something you really don’t need. Let me knows how you do.