I used to match the impedance of my guitar Taylor 414ce (with ES) on the guitar input (2.2 Mohm) my AER compact. (Connection: Taylor ES - TRS / XLR - jack mono Audix - AER)
And it works very well!
1) It is very transparent. (+ The little box that I used before Palmer who was eating low)
2) there is 17.5dB gain + 6dB due to the use of the balanced output: thus ended the feeling of not having potato ... Provided they do not put the volume knob to zero the guitar as a DI in reverse (where the risk saturation ...).
600 Ohms: 50kOhms
17.5 dB gain
20Hz-20kHz + /-3dB to use is sufficient.
Warning it can not work with all amps. You must have an input impedance of the order of MOhms (AER, Fishman Loudbox, SR tech ...), for it is not good Schertler (kOhm) ...