Problem is that we don't really know how loud you are playing. The RX-1050 is rated for 100W per channel and that seems to be a pretty "honest" rating so with M60s it should be able to play pretty darned loud without overheating.
Rather than buying new wire, I'm tempted to ask you to buy or borrow a Radio Shack SPL meter and let us know how loud you are playing. We don't know whether your problems are because your receiver is not putting out as much power as it is supposed to, or whether you just like to play really loud.
If the former, you need to get the receiver looked at (or have a friend bring their receiver/amp over) and then will probably be happy with the power that you have.
If the latter, yes a big honkin' amp would be a real good idea.
There are several people on the board who just like loud, clean music and ended up buying some fairly significant amplification to get that sound. One board member, "Tharkun", ended up with a stack of Parasound amps and a room full of M80s. There were some questions about whether he was throwing away money until people started going over and *listening* to the system... and nothing but amplifier envy after that
