sr-507 is now a few years old model, do they still have that problem with drivers falling off the headband or just better to get sr-407?

Has anybody compared SRM-006tS with SRM-600LTD? is it good idea to replace my 006ts with 600ltd for use with sr-407 or somehing better (probably still not enough for O2...)? Thanks

Now it is possible to download newest firmware directly from NAD:   http://nadelectronics.com/products/dac/M51-Direct-Digital-DAC direct link: http://nadelectronics.com/download.php?130705150850-USBM51V141.zip|M51%20software%20upgrade%20V141   Version 1.41 is still newest one, so no...

there is new driver from december 2012 for m51 on nad homepage