Do I need upgraded power cables?

@bzawa 

I don't understand not using a power conditioner with an amp. I would have guessed that conditioned power would be good for it. Do amps not need conditioning?

All mains-driven amplifiers convert incoming Alternating Current (AC) to Direct Current (DC) to power their internal power supply rails, which operate at a different voltage.  The normal arrangement is a hefty voltage transformer followed by a bridge rectifier, with the output smoothed by huge capacitors.  In general, the more expensive the amplifier, the beefier these components are and the less the impact of AC variations on the DC rail voltage.

Out of all your electronic components, an expensive power amplifier is likely to benefit least from power conditioning, especially if the power conditioner is wimpy, in my opinion!  I also think most electrical noise is generated by your own components ...

@richardbrand +1 on "an expensive power amplifier is likely to benefit least from power conditioning”

in analog design requirements, more noise / ripple / drops in the AC power requires more circuitry, higher cost components, etc., to isolate “non ideal” AC power issues from sound..

OP, many recommended plugging your amp directly into the wall to not starve the amps draw when using a shared conditioner. Two things:

1. Most are high power amps, tubes and/or mono blocks.
2. Most have installed whole house surge protection, eliminating the need for your conditioner’s surge protection.
I have a lower powered amp (Moon 330A), no whole house surge protection & never play my system loud (sounds great at lower volumes). I have my amp plugged into my 2400 & feel I am loosing nothing while adding protection. YMMV

To Start with, you have some great equipment! The first thing I’d try before I bought anything new, is to plug your amp into a different wall socket (not the same circuit as the Panamax MR4300) and listen to your favorite tunes. After a few days, do you think you hear a difference?  You may or may not. 
A couple of questions. Are you using the factory power cords to the amplifier and the Panamax?

To Start with, you have some great equipment! The first thing I’d try before I bought anything new, is to plug your amp into a different wall socket (not the same circuit as the Panamax MR4300) and listen to your favorite tunes. After a few days, do you think you hear a difference?  You may or may not. 
A couple of questions. Are you using the factory power cords to the amplifier and the Panamax?