Phase inverted preamps and Rel Subwoofers.

I have come to realize that my preamp is a “phase inverted” preamp.  This basically means that most recordings will sound better when you reverse the positive and negative wires on the back of your speaker terminals.  Since doing this my amp is getting hot.  I have Rel subs hooked to the terminals of the amp the normal way.  Could this cause the heat? Should or (can I) reverse the subs positive and negative positions on the (amp) along with the the speaker wires as well?  In this case the speakers positive and negative would be changed back the traditional way. 
You've got to test by a process of elimination. Put the connections back the way they were. No swapping. Is the amp getting hot now? If not, you are back to where you were.
Disconnect the RELs from the amp. Now swap the speaker wires. Does it get hot now? If not, reconnect the RELs. Now what's happening?
(Check to see if the RELs have a phase control.)
If the speakers are passive and isolated from everything else, there should be no problem in reversing the +lead and -lead going to the speaker(s). As for the Rel sub, connect it in the normal manner and use the Rel's 0/180 phase switch to reverse the phase. The correct position for the phase switch is the one that provides the most bass, which means that the speaker woofer is in phase with the sub driver.
First question that needs asked: did the bass of your main speakers improve when you reversed polarity of the cables?
I have Rel subs hooked to the terminals of the amp the normal way.  Could this cause the heat?


Yes.  (Overall) I definitely felt their was a noticeable improvement in bass response.
As long as your speakers are identically wired.
 Could this cause the heat?

No, BUT you could have a minor short, especially if using bare copper ends. Double check you don't have a stray conductor strand.
rel subs should have a phase switch (or setting)

read the rel manual - it is carefully written FOR YOU - the user  :)

they are very clear on how to manage phase 

I know how to phase my subwoofers.  This is in regards to the mains.  The subwoofer set up was  in question due to the heat I am experiencing -which is likely not the cause based on some of this feedback.  I switched the speaker polarity back and am still experiencing heat so not sure at this point.  
@erik_squires Thanks Eric.  I checked and they are in place.  I will just need to disconnect the subs for a period of time and check that next.  
Sub inputs should be too high an impedance to cause the amp additional stress. 
What’s your amp? Is it running in Class A? Is the bias set too high?
It’s a Modwright KWA SE.  It has a high bias and low bias switch.  I have it set on high bias.  
High bias can cause the unit to run hot. If it's new, you may need to run it on low for a period. Check with Dan Wright in case there's an issue with the thermal sensor etc.
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Talked to Dan. I’m getting the bias adjusted.