I have an L-5 CES, built in 1998. I use Gibson L-5 medium gauge strings (12 - 56), which I change frequently. The guitar always sounds flat and dull to me, and loses (acoustic) volume up the higher frets. It seems that instead of the beautiful sounds I hear from other L-5's (on You Tube, etc.), I get dull flat sounds, even with fresh strings. I have had a luthier look at it. He did a "set up," and said it was O.K. I use a Peterson strobe tuner for tuning and the intonation, but the guitar just doesn't sound or play "right." I've had it for 7 years, and have just dealt with it. I'm an amateur, and play only as a hobby. But as I get better, the sound (or lack of it) bothers me more and more. I also have an ES-347 TD, which I've had for 27 years, and it still sounds great. So my L-5 has been a disappointment. Hopefully, some members of this forum can offer some information and ideas about what my L-5 might need to play like the beautiful instrument it should be.