I had to wait to have my Martin D-18 fitted with a K&K mini. I finally had a chance to play around with my newly acquired Fender Acoustic Pro. Playing and singing into it are simply a treat. It makes my guitar louder but it does not change the sound one bit. It is my Martin, but louder. I have been using the second input as a vocal mic and it sounds great. I love this thing. I have not gigged with it yet, but it seems very powerful. As a bonus, I can plug my iphone into it and it makes a nice little sound-system.