Hi John. Yes I usually do a few masters at different levels.  PSP Xenon can do amazing things and make seriously loud masters but I still don't like pushing it that hard. 
 
What helped convince a client though was he kept importing my mixes into iTunes and he was comparing my levels to others.  And they were quieter of course.  But he had 'Soundcheck' turned off.  When I instructed him to switch it on he changed his mind.  It made a big difference.  The loud masters got squashed down quite a bit more and mine although a tiny bit lower than the others sounded much better in the end.
 
So what I learned is if you are mastering for people and they are testing in iTunes make sure 'Soundcheck' is activated.  It is not necessarily on by default or if it is then it may be turned off for whatever reason.
 
 

Jeff Evans
Hi John. Yes I usually do a few masters at different levels.  PSP Xenon can do amazing things and make seriously loud masters but I still don't like pushing it that hard. 
 
What helped convince a client though was he kept importing my mixes into iTunes and he was comparing my levels to others.  And they were quieter of course.  But he had 'Soundcheck' turned off.  When I instructed him to switch it on he changed his mind.  It made a big difference.  The loud masters got squashed down quite a bit more and mine although a tiny bit lower than the others sounded much better in the end.
 
So what I learned is if you are mastering for people and they are testing in iTunes make sure 'Soundcheck' is activated.  It is not necessarily on by default or if it is then it may be turned off for whatever reason.
 
 

Awesome thread guys.  Super useful information here.