Eventually found the answer to my own question on a French MD site (http://www.mdfr.com/forum/index.php?showtopic=15862&st=15), and the hack does indeed seem to boost volume on my European MZ-RH1 (at least on a cursory listen). In case anyone else (like me) had difficulty finding the hack, here's a translation (the hack apparently removes the European restriction to 4.5mW, to obtain the full 5mW): A) Turn the unit On (I pressed Play then Stop to 'wake it up') Slide the hold switch to on C) Whilst holding the 'T MARK' button down, enter the following key sequence: FF FF FR FR FF FR FF FR Pause Pause. This is the toughest bit, the T Mark button and 'Pause' being very close together (and small) on the MZ-RH1, so if you have fat fingers, you may need several attempts (as I did). Once successful, the display should now flash up the firmware version and become all animated (frightening!). Manual mode 1.) Press the 'Vol +' key to enter manual mode 2.) Press/slide the 'FF' button five times until the number 0113 is displayed. 3.) Press 'Vol + '/'Vol -' to enter the value 01 (US/CANADA), the original value being 81 (Europe), 05 (Hong Kong/Taiwan), or 03 (Japan). Note that only the last two digits change - the rest seem to follow some random, constantly-changing sequence. Also, getting from '81' at the end to '01' takes a lot of scrolling. 4.) Press 'Pause' to apply the change 5.) Press 'Stop' four times 6.) Turn the unit off (I removed the battery) My unit seems none the worse for wear, but I confess that seeing all that uncustomary animated activity on the display on my brand-new (expensive!) toy was quite worrying!