To clarify, I said that I have heard the lower end audio gd amplifiers and found that they had a 'dark' sound. Come to think of it, it may be due to the pairing with the LCD3 which some consider a 'dark' sounding headphone. Not the best match.. I have not heard the higher end audio gd amps (ie. Master series) so this may not apply to them. Given that DG has heard and compared the M8 to the GSX, I would take her word for it.The Master 9 seems very promising indeed.