Hard Wireing?

Don't let these people discourage you from upgrading your
receiver.All you have to do is buy one of these:
http://www.sfcable.com/YL-3215.html.Plug in your receiver in the female end then plug in a power cord you want. I did this with my sony da777es receiver and now it sounds awesome with
my ps audio lab cable plugged into it. One thing what I would do first is replace your outlet with a hubbell 8300I hospital
grade. I do not recommend installing this yourself if you
haven't done this before. Ask for qualified help. Good luck!

Agreed with the prior post about
(A) not doing it yourself.
(B) do not simply hardwire a thicker gauge cable; use a quality female plug to facilitate the attachment of a quality external power cable.
(C) replace the crap wall plugs with (at a minimum) hospital grade wall receptacles.
(D) a dedicated power line to the breaker box is the logical extension of this (eventually).

Without prejudice to (a) and (b) above, Not sure whether the cost / reward on your receiver will pan out for you. I would have the qualified technician assess it for before you jump in.

Good luck

DON'T DO IT!!!

Agree with Csontos

(1) If you capriciously hardwire in a new power cable, you may trigger a safety issue. If it causes a fire or damage, you probably violated / nullified your insurance coverage

(2) Without prejudice to the above , IMO the potential performance uptick of doing it in a receiver without the higher end power supply, likely just isn't there.

(3) Add to this the added cost of having an IEC female plug dremmeled and soldered in professionally ( if it can even be physically done with the crowded layout in a dated receiver) and then purchasing a quality external power chord , again likely isn't worth it.

If it's not working for you, trade up to new gear instead .

"These people" have been around the block a few times when it comes to equipment modifications, Speedy 9194, and were offering advice based on experience.