Alan Lofft et. all

I've taken delivery on my M60s and am in large part happy with them. Strangely when considering all the chattering about titanium tweeters being overly harsh or too bright it seems my 60s lack in top end. If I tune the treble setting to say 3:00 (or even 4:00 or 5:00 !) vs. the neutral setting at 12:00 the sound does seem improve opening up and gaining clarity and crispness. So.... my questions is:

Is it my 47 year old ears/taste?
my pathetic 'vintage' Pioneer 60W amp? - (thought poor amps lacked more in the bass dept.)
the end of the large sofa sticking out somewhat into the listening path of the left channel?

Please any feedback on the 60s performance appreciated ( Alan do you have comments on yours??)

thanks